The One With Rachel's Date - S8-E5
Visible crew/equipment: When we see Central Perk for the first time, you can see a stage light is reflected in the window. (00:05:20)
The One With Rachel's Date - S8-E5
Visible crew/equipment: When Phoebe is telling Monica about Tim, there is someone in the background with a black mug that is reflecting some of the stage lights. (00:05:20)
The One With Rachel's Date - S8-E5
Visible crew/equipment: When Rachel and Cash leave Joey's apartment, in the top-left corner a stage light is visible. (00:12:05)
The One With Rachel's Date - S8-E5
Visible crew/equipment: When Chandler tells Bob "it's his fault", there is a bin behind him that reflects the stage lights. (00:16:10)
The One With Rachel's Date - S8-E5
Visible crew/equipment: As Phoebe walks into the restaurant kitchen, a crewmember's hand is visible stopping the door from swinging too much. (00:16:50)
The One With Rachel's Date - S8-E5
Visible crew/equipment: When Ross shows up at Chandler's office and they both head out to go to the Hard Rock Cafe, just as Chandler walks out the door we can see the edge of the right wall set, allowing us to see the hallway Chandler just walked into and even Chandler's arm.
The One With Rachel's Date - S8-E5
Visible crew/equipment: While Phoebe and Tim are at Central Perk, when Tim's beeper goes off he blows Phoebe a kiss when he leaves, and as Phoebe catches that kiss and throws it away have a look at the left side of the screen, where the Central Perk wall ends we can see part of Monica's restaurant kitchen set - the door and the wall beside it. (Widescreen version).
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.