I've noticed some weird things yesterday when I was playing...
1) The Big Prank
I always thought that you can attempt the mission only one time, but last time when I played, I couldn't stop Chad from beating Gary, and just when I was going back to the Dorm I saw a star on the map, it was The Big Prank... Every time I pass Halloween and the mission becomes available, I allways fail it to see if it's available after that, and it's there every time.
2) I noticed that you can kiss Beatrise before "That Bitch", Lola as early as Chapter 2 and Pinky before "Carnival Date", and not only once, like a one time glitch, and if it is a glitch, then I encounter it on a daily basis, and it never fails me...