Bottom's Up - S1-E5
Continuity mistake: When Richie and Eddie are on the roof and Richie starts his rain dance, watch the bottom of his trousers. To start of with he pulls the hem up to around his shins. He then starts and pulls his groin or something and stops and at this point the right hand trouser falls back down his leg. Then straight afterwards in the long shot you can see that it's back up again without him pulling it up.
Continuity mistake: When Richie is telling the other 3 guys to go to the corner, he still has his hands on the wheels of his chair. But when the shot changes and Richie says "if you need the toilet then put your hand up", his arms are crossed around his waist.
Continuity mistake: When Richie falls off the ladder, it's apparent from the way he falls that he lands on his front (you just see his leg pop into shot) and that his head would be pointing towards the camera. However, instantly in the next shot we see him on his back with his head towards the wall.
Bottom's Up - S1-E5
Continuity mistake: When they are first on the roof, Richie is seen looking through a telescope on a stand. However, it is gone a few moments later, and doesn't appear at all for the rest of the episode.
Bottom's Up - S1-E5
Continuity mistake: When Eddie goes down to fight the looters the sky is totally blue. But all of 2 minutes later when he comes back on the roof, the sky is totally grey. Not a chance could that happen so quickly.