Continuity mistake: When helmet-wearing Vicar Joey taunts Rachel one too many times she turns the tables on him, so when Joey backs away from Rachel he gets pushed up against the front door, and although he can't move, in the shot facing Joey he's at the left side of the door, but in the side shots he's at the right side of the door.Super Grover
Continuity mistake: Chandler and Monica are having dinner with her parents. He asks Jack how he and Judy got engaged. He starts, "Well I'd gotten Judy pregnant..." Then they talk about how Jack told Monica's friends a "scary story" about how Judy got pregnant because her method of birth control, her diaphragm, had malfunctioned (damaged by a dog). In the rest of the show, however, we are continually hearing that the firstborn, Ross, was "a medical marvel" and that they thought Judy was barren. This apparently is the main reason why they love Ross more than Monica.