Continuity mistake: Chris puts a video recorder in his room to try to capture the angry monkey in his closet to show Peter and Lois. He views the tape the next day and sees Peter and Quagmire enter his room. Quagmire punches Chris in the eye and bruises, it but when we see Chris the very next day, there's no black eye.
Continuity mistake: Peter says "Oh crap" as soon as he realises Ernie the Giant Chicken is looking at him in the window. When the camera pans over to Ernie, he is standing an inch away from the glass. It then cuts to a wide angle where Ernie jumps through the window, and he has instantly moved back a few inches.