The One With Five Steaks and an Eggplant - S2-E5
Plot hole: Chandler has always loaned Joey money for various things (rent, acting classes, Christmas gifts, etc), so he shouldn't be surprised to learn that Joey doesn't have money for fancy dinners or birthday celebrations. Plus, Joey never seems to have a problem taking money/handouts from Chandler - why now? Also, Chandler explains that they're buying Ross a cake ($20), but why doesn't Monica (the chef and his sister) just make him one? (00:07:50)
The One Where Ross and Rachel...You Know - S2-E15
Plot hole: Rachel says she didn't want to wear her glasses on their first date. Rachel doesn't wear glasses.
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.