The One With The Ball - S5-E21
Other mistake: The guys start the ball-throwing game at around 2 in the afternoon. Later, they mention that it's been going for 10 hours, making it around midnight. Why would Rachel, who never cooks, be defrosting a chicken? And why would she be doing so at midnight?
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.