some other indications of the authenticity of the torah.
the laws of shmita (Parsha Behar) (every seven years everyone in israel must stop working the land for the whole year. God promises to provide a bumper crop prior to the Shmita year to sustain the Jewish people). furthermore, in the yovel year this would be two consecutive years where noone planted anything. What human in his right mind would fabricate such a claim and risk mass starvation? (if this were agricultural reasons, it would not be necessary to stop all the land simultaneously and it would be crazy to promise a bumper crop after six straight years of harvesting the land. Usually the opposite happens after 6 straight years.)
3 times a year, every year, during the temple era, all Jewish males are commanded to leave their homes and go to Jerusalem for the festivals. God promised: "Nobody will desire your land while you are going up to see the face of the Lord your God three times in the year." (Ex 34:24) Who else could make such a claim but God? No human being in his right mind would enact such a law, leaving his army vulnerable to being encircled and easily defeated. Turns out it proved true that no foreign nation ever came up to take the land of the Jews during their festivals prior to the destruction of Jerusalem 400+ years later.
Kosher. The torah informs us that there is only one animal that has split hooves and does not chew its cud - the pig. Who else but God could claim this? (see this link for more on this: http://www.aish.com/jl/b/bb/104491254.html )
"all fish with scales have moving fins" - who else but God can claim this. (see above link). (some invoke the "sea snake" or "sea eel" as a "refutation" but these scales are embedded in the skin unlike normal fish which are armor-like and come off without peeling off the skin. the hebrew word for scales "kaskasim" is the same as for armor. see: this or this)
The torah's prophecies of the return of the Jews to Israel. (can a nation exiled from its homeland and splintered into a dozen minor ethnic groups for 2,000 years, have the ability and resolve to return en masse to their homeland and become a universally recognized world power?)
Miraculous victories of the israeli army in the early wars (see for example: http://www.chabad.org/multimedia/timeline_cdo/aid/525341/jewish/Introduction.htm or http://www.benmelech.org/z-def/english/israel-bailey.htm) Even Ben Gurion who was a secular Jew is quoted as saying: "In Israel, in order to be a realist you must believe in miracles".
The Tzadikim - those who have had the merit and opportunity of meeting with the Tzadikim (righteous sages) of the generation know that even today, we can find shadows of "prophecy".
the infinite wisdom/depth of the Torah, which is evident to all who study it in depth.
The uniqueness of the hebrew language. There is something much more to it than plain convention as explained here. see also DNA of creation by Rabbi Becher here or the book "Letters of Fire" by Rabbi Matityahu Glazerson
Jews don't go around trying to convert nonjews. on the contrary, they try to discourage potential converts, that it will be too much for them to take on. This is due to confidence in the pact of God with Abraham that Judaism will never disappear as explained here. We see its effects today, as Mark Twain wondered: "The Jew saw them all, survived them all, and is now what he always was, exhibiting no decadence, no infirmaties, of age, no weakening of his parts, no slowing of his energies, no dulling of his alert but aggressive mind. All things are mortal but the Jews; all other forces pass, but he remains. What is the secret of his immortality?"
The uniqueness of the Jewish people, in terms of cultural survival as explained in this lecture by Rabbi Mordechai Becher. This indicates a special providence on the Jews more than any other nations as explained there. We also find a uniqueness around the jewish people in terms of intellectual abilities. They have received an extremely disproportionate number of nobel prizes. This indicates "something" unique about the Jews.
Antisemitism - The Talmud (Tractate Shabbos 69) cites the source of anti-Semitism using a play on words: The Torah - the source of the Jewish system of laws, values and moral standards - was received at Mount Sinai. The Hebrew pronunciation of "Sinai" is almost identical to the Hebrew word for "hatred" - sinah. "Why was the Torah given on a mountain called Sinai?" asks the Talmud. "Because the great sinah - the tremendous hatred aimed at the Jew - emanates from Sinai." I think we can confirm the existence of this irrational hatred throughout history. Even today, the UN passes more resolutions against Israel than pretty much the entire world combined. Some Jews have tried to cure this hatred by abandoning the torah and becoming like the nations but history shows it has resulted in the opposite effect, as predicted in the verse (Ezekiel 20) "When you say, 'Let us be like the nations, like the peoples of other countries...' As I live says the Lord GOD - I will rule over you with a strong hand, an outstretched arm, and outpoured wrath".
The special providence given to those who truly dedicate themselves to torah study. The Vilna Gaon for example reportedly achieved superhuman levels of torah wisdom as explained here and here. More recently, it is reported in the book "HaSod" by (Y. Hershkowitz) about Rabbi Yosef Shalom Elyashiv that his grasp of the entire spectrum of torah depth was miraculous. He was able to answer the most complicated halachic questions instantly, even those intertwined in multiple complex sections in the talmud over many tractates. Many times the head judge of the Rabbinical Court in Jerusalem was asked to rule on such complicated questions. He would answer: I can research this and give you an answer in several days, or you can go to Rabbi Elyashiv and get a fully reliable answer instantly.
The uniquenes of the torah. It has been translated in more languages than any other book. This indicates a special providence.
Judaism is the mother of all monotheist religions. Scientific inquiry supports the idea that the world functions through a unifying force as explained in this lecture by Rabbi Mordechai Becher. This is an indication that if the universe is run by the divine then there is only one Divinity.
Two more points brought by Rabbi Yaakov Emden (200 years ago, quoted in Masoret Yisrael edition of Chovos Halevavos end of gate 10):
The sign of the truth of these things are from two faithful, visible,
One, our situation and survival in this long exile, which the Creator
fulfilled His promise: "But despite all this, while they are in the
land of their enemies, I will not despise them nor will I reject them
to annihilate them, thereby breaking My covenant that is with them,
for I am the L-ord their G-d" (Vayikra 26:44)...
Two, the matter of our land, because from the day we went out of it,
no nation was able to dwell in it, it was like a woman who's husband
went on a faraway trip, and she waits for him, and the verse "I will
make the Land desolate, so that it will become desolate [also] of your
enemies who live in it" (Vayikra 26:32), tells us it is guarded for
us...all this are clear signs that our hope is not lost and G-d's love
has not left us, and on this eternal love is based Shir Hashirim, and
just like G-d loves us a strong love, "Torrents of water are not able
to extinguish the love" (Shir Hashirim 8:7), so too it is our duty to
show our powerful and complete love, like "As water reflects a face
back to a face, so one's heart is reflected back to him by another"
Rabbi Matityahu Solomon, the mashgiach of the Lakewood Yeshiva in New Jersey also brings down a different version of Rabbi Emden's argument in his commentary to the Shaar Bechina ch.5:
We do not need to contemplate on the great miracles of the Exodus, in
order to examine and demonstrate G-d's goodness and infinite power.
For behold, we have a faithful witness which cannot be denied - our
survival during this exile among the nations. It is proper to quote
the holy words of Rabbi Yaakov Emden (sidur beit kel):
"Who is so blind as to not see the divine providence below, that His
eyes are on them always. How could the denier of providence not be
ashamed and stand disgraced? He who examines our unique situation and
standing in the world. We the exiled nation, a dispersed sheep. After
all the troubles and shifts for two thousands years. No nation in the
world is as pursued as us. How great have been our troubles! How
powerful have been those who lifted their heads against us from our
earliest beginnings - to exterminate us, root us out, and eradicate
us, due to their intense hatred which stems from jealousy. They have
brought on us great sufferings but were never able to triumph over us,
to eliminate us and destroy us. All these ancient, powerful nations -
have gone by, their strength has withered, their protection has eroded
- but we who cling to G-d are all alive today (Deut. 4:4). We have not lost in this long, intense exile even a single letter or vowel of the
written Torah. The words of the Sages (oral law) endured. The hand of
time did not prevail over us, they were not able to prevail over us.
What will the sharp philosopher answer to this? Can the hand of chance
do all this? I swear by my soul, for when contemplating these things,
they are greater in my eyes than all the great open miracles G-d has
performed for our forefathers in Egypt, the Sinai Desert, and in the
land of Israel. (the author wrote that the miracle of our survival in
this exile is equal to the miracles of Egypt, but Rabbi Yaakov Emden
holds that it is an even greater miracle) The longer the exile, the
more the miracle is confirmed, and G-d's strength and power becomes
apparent. For the prophets already saw the exile's intensity,
complaining and moaning on its amazing protracted length before it
happened. Behold, none of their words fell to the ground (failed to
happen)..." End quote
(Rabbi Solomon continues) As Moshe Rabeinu told us from the outset that such and such as trouble
would befall us, and thus it happened. Likewise, for all of our exile
- the prophets already predicted what will happen. For all the persecutions and pursuits that befell us, such as the holocaust, it is
all spelled out in the verses of the Torah which speak on those
times... Can we not see these things with our own eyes?! Behold, only
by examining and contemplating is it possible to see them. Without
contemplating them, we remain totally blind.
for yet more points I put together see here