Continuity mistake: In the deleted scene on the DVDs Chandler is leaving the security interview with his holdall over his shoulder by the short strap. The camera cuts to outside the room and the holdall is now level with his legs. (Mistakes in Deleted scenes are valid if they are only in that scene which this is.)
Continuity mistake: When Joey and Phoebe are talking about his co-star spitting on him, and Phoebe says that she gets spit on at work, Joey puts his hand on her arm. Then in the next shot, when Monica and Chandler are walking along, Joey puts his hand on Phoebe again.
Continuity mistake: At the end when Rachel comes into the coffee house and sees Mona with Ross, she is holding a brown paper bag. When you see her in the background, the the top of the paper bag is rolled over away from her. When the camera switches to just Rachel, the paper bag is the other way around with the top rolled over towards her.