Goofs

In the opening when Phoebe runs into the room she is wearing a jacket but when she is talking to Monica she doesn't have her jacket on.

When Phoebe and Monica are on the double date, the glass of wine on the table moves without anyone having a drink.

While slow-dancing, Chloe's left hand jumps from Ross's waist to his shoulder and back again in between shots.

When Chloe invites Ross to dance, she puts two beer bottles with short necks on the bar, however on the next shot they are nowhere to be seen.

In the heat of her argument with Ross, Rachel defends the long hours she has been putting in at her job by saying "do you know that this is the first time in my life I'm doing something I'm actually good at?!" Earlier though, she made a mistake with the invoice: "I think I just shipped 3,000 bras to personnel!" Response: However, this was likely a small error caused by being unfamiliar with the software, when Mark created a dummy invoice to show her the process, and she sent it instead of deleting it. She would have been very good in the job itself, working as an assistant to a buyer, given her expertise in retail and fashion and her dedication to the job.

Phoebe needs an English translator, but in later seasons it is revealed she is fluent in French. The level of her fluency and accent would be difficult to achieve is such little time. However, only the translator speaks French with Monica and it is not clear that the diplomat also speaks French, since he is Eastern European.

When Ross accidentally lights the flowers on fire at Rachel's office, the candle is not touching or close enough to the flowers and the flame starts in the center of the flowers away from the candle's flame.

Sergei's translator wouldn't be able to suddenly resign from his post without being reprimanded by the government of his home country.