The One With The Bullies - S2-E21
Visible crew/equipment: While driving the cab, Phoebe is wearing a blue shirt. When the car stops suddenly, a crew member wearing a white shirt is visible driving the car.
The One After the Superbowl, part 2 - S2-E13
Visible crew/equipment: When Joey walks into the bathroom and starts whistling, the shadows of the camera and a passing crewmember can be seen on the door of Chandler's cubicle, then the camera's shadow moves as Joey walks toward Chandler and also when Joey's about to stand on the toilet.
The One Where Ross and Rachel...You Know - S2-E15
Visible crew/equipment: While Ross is trying to fix the position of the cavemen in the museum, a boom mic can be seen above his head.
The One Where Ross and Rachel...You Know - S2-E15
Visible crew/equipment: When Rachel's talking about when Richard kissed her when she was a little girl, you can see the boom mic above her head. (00:16:10)
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.