The One With Monica and Chandler's Wedding, Part 2 - S7-E24
Revealing mistake: At the point in the ceremony where Joey forgets the rings, the camera pans out and you see Chandler step sidewards to get the ring from Ross, and Monica step sidewards to get the ring from Rachel and Phoebe. As Monica moves, her dress slides across and one of her feet is revealed; it has what looks like a brown boot or heavy brown shoe on it. (00:20:05)
The One With Monica and Chandler's Wedding, Part 2 - S7-E24
Continuity mistake: As Chandler meets Monica at the altar, Monica's hand switches from holding Chandler's hand, to holding the flowers, with no time to do so. (00:40:40)
The One With Monica and Chandler's Wedding, Part 2 - S7-E24
Continuity mistake: The way Phoebe holds her flowers when told to smile changes depending on the angle. (00:04:30)
The One With Monica and Chandler's Wedding, Part 2 - S7-E24
Continuity mistake: During an earlier episode Monica gave up her dream wedding dress so Chandler could have The Swing Kings at their wedding. So it is a little surprising that the band they actually have are called Jungle Swing.
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.