Moe comes to the meeting for parents and appears to be very active, although he has no children.
Although Mrs. Muntz's bra slides down and reveals her chest, she visibly doesn't care about that. Also, Ned Flanders who sits right in front of her, doesn't complain at all.
Mrs. Muntz at one point belches in nearly the exact same manner as Barney Gumble, playing into the urban legend that Nelson Muntz and Barney are somehow related due to their similar physical appearances.
Julius Hibbert is obviously addicted to morphine which explains his laughing.
When Homer wakes up and thinks Eduardo was just a dream, he is lying on Marge's side of bed.
Eduardo's last name is "Barcelona" which is the second biggest city in Spain.
Lewis's essay about holiday doesn't have his surname on it, in contrast with with classmates.
For those who have good eyes, if you look closely at the test papers Lisa finds in Bart's backpack, one of the papers belongs to a student named Burt Symmson. There was an octopus on his paper, giving a hint that he might be a kindergartener, 1st, or 2nd grader.
Lisa only thought that Bart was cheating just because he had 100% on his tests, which by itself does not prove that Bart was not following the system of students trusting each other not to cheat. Lisa just wanted herself to be in the right when she forced Bart to turn himself in and wouldn't admit that she was wrong to think that he was cheating just based on him getting 100% on everything. Besides, if Bart really was cheating, it's very likely that somebody else would have already turned him in.
The detention quilt says "detention of '08", but this episode aired in 2013.
Cookie Kwan is shown at the PTA meeting, even though her only child is a baby.
Lisa ripped part of her hair off during one of the conversations with Bart, but some scenes later, her hair is intact.