The One With Phoebe's Uterus - S4-E11
Continuity mistake: At the beginning, Alice and Frank tell Phoebe that they have been trying to get pregnant. When Alice says, "You know, no one's getting any younger", Frank looks at Alice and laughs. In the next shot however, he is looking at Phoebe and doesn't seem to laugh. (00:01:00)
The One With The Fake Party - S4-E16
Continuity mistake: When Rachel is talking to Joshua near the drinks table at the party, he is holding a blue cup in his left hand and nothing in his right (this is most obvious when she's offering him a cherry). When she begins to choke, he raises his empty right hand to pat her on the back, then when she walks away there is suddenly a bottle in his raised hand. The shot changes, and his hand is again empty and he reaches down to the table and picks up the same bottle. (00:08:30)
The One With The Fake Party - S4-E16
Continuity mistake: When Rachel is in her bedroom dressed as a cheerleader with Joshua, the sleeve of her sweater on her right arm keeps moving up and down. (00:15:00)
The One With Rachel's Crush - S4-E13
Continuity mistake: At the start of this episode when Rachel comes in, you can see a bit of wooden floor by the door (carpet's visible in other shots). However, Monica doesn't pull up the carpet until later in the episode, after the apartment's tidier. (00:02:10)
The One With The Fake Party - S4-E16
Continuity mistake: While Joey spins the bottle and it keeps pointing to Emily, in the shots facing Ross the door behind him goes back and forth from being either closed or wide open, depending on the angle of the shot.
The One With The Fake Party - S4-E16
Continuity mistake: After Rachel spins the bottle and it points to Joshua, when she crawls toward him on her hands and knees the bottle is in front of her knees in the shots facing her, but in the shot facing Joshua the bottle is at her side, near her foot.
The One With All The Wedding Dresses - S4-E20
Continuity mistake: When Rachel suggests to Joshua that they should get married, he says "What?", and his hands are out in front of him. The camera cuts to a wide shot and his hands are now on his thighs. Cut back to Joshua and his hands are now out in front of him with his fingers interlocked.
The One With The 'Cuffs - S4-E3
Continuity mistake: Rachel is telling Chandler to break off his relationship with Joanna, who had walked through the room and went into Chandler's bedroom, shutting the door. By the end of the conversation between Chandler and Rachel, the door is open but no one has entered or left the room.
The One With The Free Porn - S4-E17
Continuity mistake: In the scene where Phoebe tells the gang about her "Relaxitaxi" idea the position of Chandler's left arm changes between shots. In the frontal shots it's lying the back of the chair and in the shots from behind it's wrapped around Monica's shoulder.
The One Where Chandler Crosses The Line - S4-E7
Continuity mistake: In the final scene wherein Phoebe finally agrees to play guitar again, Ross moves from the armchair to the sofa. As he sits down, his arm is by his side, but when the camera angle shifts, it is on the back of the sofa. (00:20:50)
The One With The Worst Best Man Ever - S4-E22
Continuity mistake: In the scene where the veterinarian gives the ring back to Ross, there is a dog in the background that goes from standing up to lying down to standing again depending on the shot.
The One With The Worst Best Man Ever - S4-E22
Continuity mistake: When Joey says that Ross needs to choose his best man before handing out of the ring, the camera cuts to Chandler. In the background you can see Joey getting up from the chair, but when it cuts back to Joey he is sitting down and then gets up in that shot. (00:02:01)
The One With Rachel's Crush - S4-E13
Continuity mistake: When Monica waves the smell of cookies in the guys' new apartment, you see Ross right in front of Phoebe when they walk over, then you see Ross in front of Rachel as they go in.
The One With The Jellyfish - S4-E1
Continuity mistake: When Monica gets stung by the jellyfish they are standing on a part of the beach that is wet and close to the surf but when she is saying "damn the jellyfish" the part they are standing on is dry and further from the water.
The One With The Jellyfish - S4-E1
Continuity mistake: In the last few seconds of season 3, Ross closes the door immediately after he steps through it. However, in the opening seconds of season 4, we see this same event from the other side of the door. This time however, Ross doesn't close the door for at least 15-20 seconds after entering the room.
The One With The Free Porn - S4-E17
Continuity mistake: In the beginning when Rachel says "Do we really have to watch this while we eat." From the front view Rachel's arms are crossed and then from the back their are by her side and back with no time to turn.
The One With All The Haste - S4-E19
Continuity mistake: The singing neighbor is more than halfway done tying his tie but when Rachel yells at him, the tie is merely draped around his neck.
The One With The Dirty Girl - S4-E6
Continuity mistake: Rachel is working on the crossword puzzle and her legs are crossed (first left over right) and they switch back and forth between shots (about four times) without any time to do so.
The One With The Embryos - S4-E12
Continuity mistake: The part in Chandler's hair switches from left to right throughout the episode.
The One With Joey's New Girlfriend - S4-E5
Continuity mistake: When Ross goes to Amanda's house for a date you see her two children sitting on the couch. The little boy with blonde hair is sitting down, when it cuts to Ross and Amanda talking the boy is standing up on the couch, the next shot he's sat down as Amanda walks out the door.
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.