The One Where They're Going To PARTY! - S4-E9
Continuity mistake: When Chandler answers the phone and it's Gandalf calling to cancel, Ross is just opening the fridge, but the shot cuts to Chandler with the phone and Ross is putting two beers down on the side next to him - too quick to have got them there from the fridge. (00:05:35)
The One Where They're Going To PARTY! - S4-E9
Continuity mistake: When Joanna stops Rachel from leaving work Rachel's holding her handbag and jacket, and there's still one bag hanging on the wall hook, but when Joanna mentions the "drinking binge" there are two bags hanging from the hook, then it's back to just one bag, yet when Joanna calls Sophie there's nothing on the hook and Rachel has both bags.
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.