The One In Vegas, Part 1 - S5-E23
Continuity mistake: Chandler comes down to find Monica and sees that she's playing some game and having fun. He makes a sad and dejected face. The scene cuts back to Monica, and then to the exact same shot again of Chandler making the sad and dejected face. (00:22:00)
The One With The Ball - S5-E21
Visible crew/equipment: A stage light can be seen above Ross when he asks Rachel how much she paid for her cat. (00:04:05)
The One With Ross's Sandwich - S5-E9
Continuity mistake: When Ross is in Central Perk talking about his day at work and how he is not going to work for a while because of his rage, watch his cotton candy. It changes in sizes and shape a lot, from big and uncircular to small and circular. (00:14:50)
The One With All The Kissing - S5-E2
Continuity mistake: In The One With All The Kissing, Phoebe grabs a photo of the other 5 by the Tower of London. When we see a shot of her a few seconds later drawing herself into the photo, it's a different photograph. (00:07:25)
The One Where Rachel Smokes - S5-E18
Continuity mistake: When Ben is playing with the building blocks, they change with each shot, and he holds different coloured blocks each time. (00:15:20)
Continuity mistake: When the group is in the coffee house discussing Kip there is a bag on the table in front of Monica. When Rachel enters she places her bag on top of the bag already sitting there. Toward the end of this scene Rachel's bag then disappears and only the original bag is now sitting there. (00:13:10)
The One With The Ball - S5-E21
Visible crew/equipment: A cameraman can be seen in the TV when Rachel is on about the cat she had as a kid. (00:04:25)
The One With The Inappropriate Sister - S5-E10
Visible crew/equipment: When Ross and Monica are wrestling, the stagelights can be seen in the tv. (00:12:45)
The One Where Everybody Finds Out - S5-E14
Continuity mistake: Monica and Chandler are deciding what to do about Phoebe's flirting; the shot cuts to her and Rachel, and Rachel's right hand is on her chin. In the next shot, it's her left hand on her chin. (00:12:00)
Plot hole: In TOW Ross tells Rachel he cannot see her following a promise to Emily, the rest of the friends go into Monica's bedroom. Joey hauls out a box from under the bed, saying that he's been hiding it there since Ross said the wrong name at the wedding. Surely Monica, with her obsession for keeping the place clean, would have noticed a box under her bed? (00:04:10)
The One With The Ride-Along - S5-E20
Continuity mistake: Toward the end of the episode, Rachel is back in Ross' apartment, trying to mend the ornament she broke when she was in there earlier. Ross comes in unexpectedly and she tosses the broken pieces into the lightshade, leaving the glue on the side table. In subsequent shots, the glue goes from lying on its side, to standing up, a number of times. (00:16:00)
The One With The Triplets - S5-E3
Revealing mistake: When the doctor says, "Here comes the head," it is very obvious that there are feet coming out. (00:14:50)
The One With Rachel's Inadvertent Kiss - S5-E17
Visible crew/equipment: After Monica tells Rachel that a guy from Ralph Lauren called and they want her for a second interview, when Rachel walks toward the TV and then when she stands in front of the TV, we can see a few tapes marks on the floor. One of those tape marks is also visible in one of Joey's closeups.
The One Where Everybody Finds Out - S5-E14
Factual error: Phoebe holds up a bag of quarters that is almost the size of her head. This would be physically impossible for anyone except perhaps the world's strongest weight-lifters. Quarters are exceptionally heavy for their size. Two rolls weigh exactly a pound. It would take at least 300-400 rolls worth of quarters to fill up the bag Phoebe is holding, which means she is lifting 150-200+ pounds, primarily with one arm. (00:08:40)
The One With Joey's Big Break - S5-E22
Factual error: In the scene where Joey is supposedly in the Nevada desert, Saquaro cacti are seen in the background indicating that the scene was shot in Arizona or Mexico.
The One With The Triplets - S5-E3
Visible crew/equipment: In the scene with Joey filming Phoebe and Phoebe saying, "Please don't hurt me," Joey zooms out and you can see the camera that is just about to film them. (00:00:35)
The One With The Ball - S5-E21
Continuity mistake: When Rachel mentions the cat's name, Ross has the ball. The camera does an instant cut, and Joey now has the ball. Ross did not throw the ball, as you hear the ball being caught every other time. (00:04:50)
The One With Ross's Sandwich - S5-E9
Revealing mistake: Joey's bucket of chicken is, rather obviously, a KFC bucket with "Finger Lickin' Chicken" stuck over the original KFC lettering - you can even see the picture of Col. Sanders. (00:17:10)
The One With All The Thanksgivings - S5-E8
Continuity mistake: When Phoebe is trying to turn on the TV, her necklace moves without her touching it. (00:00:15)
The One With All The Resolutions - S5-E11
Character mistake: In one of the scenes where Phoebe is teaching Joey guitar, she asks him to demonstrate the "Iceberg" chord. To refresh his memory, Joey refers to the chord as "G Sharp." In reality, the only way to play a G Sharp chord is with a barre chord, and as such the fingering is not exclusive to it.
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.