The One With The Ballroom Dancing - S4-E4
Continuity mistake: In the Central Perk scene when Joey is telling Monica and Rachel about the dancing, Monica's legs are crossed left over right and then right over left, and back again. (00:10:55)
The One With The Ballroom Dancing - S4-E4
Other mistake: Right at the end of the episode, Phoebe's got a job interview. We see the outside of a massage parlour, but the name on the awning has been superimposed - it moves about a bit while the shot itself is still. (00:20:45)
The One With The Ballroom Dancing - S4-E4
Continuity mistake: While Treeger chews out Rachel for not properly disposing the pizza box in the trash chute, the room's door is closed, then wide open, and then closed again.
The One With The Ballroom Dancing - S4-E4
Other mistake: In the scene where Rachel is going to take out the trash, Monica tells her the garbage room is the 3rd door on the left. However, when Rachel comes back with the pizza box and Monica leaves for the garbage room, she leaves the apartment and walks towards the right - there are no doors that way, just the stairs. (00:00:50)
The One With The Ballroom Dancing - S4-E4
Revealing mistake: During the end bit, before we get to see Phoebe when she is being interviewed at Lara and Jeni's Massage, if you look closely at the name of the massage parlor, you'll see that, although the camera shakes and bumps, the words stay on the very same spot on the screen. Obviously the canopy was blank and the name was digitally added later.
The One With The Ballroom Dancing - S4-E4
Visible crew/equipment: When Phoebe and Rick are sat on the massage table, keep an eye behind Phoebe's head when the camera is on her, particularly after Rick says, "I can always find another masseuse." You can see the shadow of the boom mic moving.
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.