I heard a Dvar Torah regarding the 3 sons of Noach, according to which it would indicate that they were triplets. Are there any commentaries that indicate that Shem Cham and Yafes were triplets?
Rashi to Bereishit 10:21 says that Yafet was two years older than Shem.
...When Scripture says (11:10): “Shem was a hundred years old, etc.” two years after the Flood, you must say that Japheth was the elder, because Noah was five hundred years old when he first had children, and the Flood came to pass in the six hundredth year. Consequently, the eldest of his sons was a hundred years old [at the time of the Flood], and Shem did not reach [the age of] a hundred until two years after the Flood. — [from Gen. Rabbah 37:7]
Although it is a dispute among the different Rishonim which one was older, the Pasuk (11:10) that says Shem was a hundred years old two years after the Mabul strongly implies that the others were not the same age.
So I guess my contribution to the answer is that it isn't just Rashi on that verse, and on the verse which introduce them in the order of Shem, Cham and Yafes, that sites their ages, and they don't say triplets.
That doesn't exclude learning that they are triplets, but it makes it difficult. It is completely incompatible with Rashi (not just his opinion, but his whole approach to 11:10), for what that is worth.