The Jon Lovitz character always bugged me, well the way he was used anyway. He showed up as a pot-addled restauranteur in the first season, and annoyed Monica, Rachel and Phoebe. Phoebe got her own back at the end of the episode by giving him (think his name was Steve) a painful massage.
Then all the way forward to the final season, Lovitz returned, presumably playing the same guy (still named Steve IIRC) and still possessing similar traits to Season 1 Steve. Phoebe has obviously kept in contact somehow with him for all these years to set him up on a date with Rachel, a date designed to be terrible so Rachel would realise how much Ross means to her.
But the major annoyance is that Rachel seemingly doesn't remember or recognise him at all, and therefore doesn't cotton on instantly that's she's been set up on a deliberately bad date. Even when Steve immediately begins to act peculiarly it doesn't trigger any memories of him all those years ago causing havoc in Monica's kitchen, despite Rachel persuading Monica to hire her as a waitress that evening and bearing witness to Steve's stoned behaviour.
Just kind of annoying that Rachel wouldn't even reference her previous encounter with Steve, either on the date or to Phoebe or Monica afterwards. It's like she suffered some sort of Lovitz amnesia