The One With The Engagement Picture - S7-E5
Continuity mistake: When 'Hums While He Pees' hands Phoebe the tickets for the ballroom dancing, they switch hands depending on the camera angle. She takes them in her right hand, but in the shot from behind she has them in her left hand. (00:08:25)
The One With The Engagement Picture - S7-E5
Revealing mistake: In the shot of the paper with the picture of Monica and Joey, the anouncement written there starts out fine, but near the end the middle part is just repeated again. (00:20:35)
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.