Revealing mistake: When Chang's paint bomb explodes, pay attention to the background. You will see paint exploding from three different points on the ground. (One to the center, one to the left and one to the right) The only problem is that there was only one paint bomb in the center, so it makes no sense that there are 3 explosions from different points.
Continuity mistake: We know from this episode that Pierce's father is alive, but at the beginning of episode 1-7 Pierce's mother is on the other end of the phone and speaks about seeing his father's "ghost," as if his father has passed away. (00:02:00)
Continuity mistake: When the group is making posters for the MacGuffin Institute meeting, Annie holds up a poster saying "Welcome Archie" to show off name brand glitter but the character of Archie isn't introduced until the next episode (in which the banner shows up again). (00:03:11)