Continuity mistake: When Joey is reading his speech about all the giving and receiving, Chandler has his legs on the table at the coffee shop. You can see his shoes on the table when they show Joey, but when they change the shot to Chandler his legs are on the floor and crossed.
Continuity mistake: When Janine goes into the hallway to apologize to Monica about her behavior at dinner, she runs into Monica who says, "What did I tell you about the hall?" As she says this, she is pointing her right forefinger at Janine and her right shoulder is leaned in closer to her. When Janine says "I was just coming over here to apologize for my behavior," the camera cuts to Monica, who is now standing with her left shoulder leaning in toward her. The camera cuts back to Janine as she says "I'd really like it if we could be friends" and then back to Monica for her next line, where she again has switched to her right shoulder leaning toward Janine.