In general, the concept of דברים שבלב אינם דברים (see Kiddushin 48b) dictates that if one verbally expresses his participation in a legal or halachic process, it is legally binding even if one didn't actually mean it.
Accordingly, if you were to ask someone for the price of an item and the merchant tells you to take it for free – and you performed a kinyan – ...
The Rambam (Hil. Avodah Zarah 12:3) gives the following list:
וכל מצות עשה שהיא מזמן לזמן ואינה תדירה נשים פטורות חוץ מקידוש היום ואכילת מצה בלילי הפסח ואכילת הפסח ושחיטתו והקהל ושמחה שהנשים חייבות
The Avodat Hamelech (ibid.) notes a number of additional mitzvot which it seems women are obligated in as well:
מנה רבנו רק ששה מצות עשה קידוש היום, אכילת מצה, ...
I would ask the question regarding Milah or Schitah which are not extensively discussed in the mishna either, although both are clearly more strict than safrus (milah has an isur karas and Schitah a lav).
The common factor between these mitzvos are that they are hand-ons mitzva and cannot be learnt without a mentor, and does not suffice with a mishna.
Tosafos on megilla 4a asks this question and gives 2 answers.
That gam haio bioso neis is rabbinic . The hekesh by matza is deoraisa.
Gam haio bioso neis would obligate women deoraisa in matza, however you would learn out from the hekesh 15 15 from Sukka to exempt them. Therefore you need the hekesh from chametz to matza to obligate them.