Joey says in his best man speech at the rehearsal that he met Ross "in this coffeehouse back home" . We know from a previous episode that he met him in the same place, yet it was not a coffeehouse but a pool club/bar then.
During the rehearsal dinner, Judy Geller says that this may be the only wedding she gets to throw. This is, in fact, a recurring error throughout the second half of the season and is perpetuated by several characters, including Ross himself. This is especially inexplicable as Ross, at least, should know that he was previously married to Carol, the mother of his son.
Hugh Laurie is credited as "The Gentleman on the Phone" instead of "The Gentleman on the Plane" - an obvious result of incorrect interpretation of someone's handwriting. This error is corrected on the DVD.