All are obligated in Re'iyah, with 12 exceptions.

Beis Shamai and Beis Hillel argue about which "Katan" is exempt from Re'iyah (must he be able to walk on his own).

Beis Shamai and Beis Hillel argue what are the minimum values of the Korban Re'iyah and Korban Chagigah (2 Me'os or 1 Me'ah).

Question: Whom does the word "all" in the Mishnah include?

Answers: It includes a number of people who are not listed explicitly -

It includes either one who was lame on the first day of Yom Tov but became well on the next day.

Or it includes one who is blind in one eye (in contrast to R. Yochanan ben Dehavai's opinion).

Or it includes one who is half slave and half free, and is in accordance with the Mishnah Acharonah.

Beis Shamai and Beis Hillel originally argued about whether a person who is half slave and half free must be freed by his owner, or may be left to live in that state.

Beis Hillel rescinded and agreed with Beis Shamai, that one who is half slave and half free must be completely freed so that he be able to marry and have children.

The Cheresh of the Mishnah is one who has no De'ah, like a Shoteh and a Katan.

The Mishnah implies that a partial Cheresh (who hears but cannot speak or who speaks but cannot hear) is obligated in all Mitzvos.

Question: A Beraisa states that a partial Cheresh is exempt from Re'iyah!