How can one gather the entire community in front of the Ohel Mo'ed?
Rashi: This is one of the places where a small space contained a lot of people. 1
Rosh, Moshav Zekenim: Moshe asked how everyone will be able to fit there. Hashem said, the Shamayim was like Dok (a film) in the eye, and I widened it from one end of the world to the other! Similarly, in the future I will widen the world to fit all those who will be revived.
Why was it necessary to gather all of Yisrael in order to dress Aharon?
Moshav Zekenim: This was to aggrandize Aharon, to show Yisrael that Hashem chose him to wear Bigdei Kodesh and do Avodas Hashem, so they will know that Hashem forgave him for the Egel.
QUESTIONS ON RASHI
Rashi writes that this was on the 23rd of Adar, before the Mishkan was erected. How can this be? It says "Pesach Ohel Mo'ed"!
Refer to 8:33:151:1.