When Niles and Daphne are driving down the driveway, Niles' hair is noticeably shorter than in the previous episode--which in TV land took place on the same day, but four months in real time.
(At 00:01:29) The strap on Daphne's wedding dress keeps moving between over her shoulder and across her arm between camera cuts.
Donny launches a breach of contract lawsuit against Daphne for backing out of their wedding, in which he seeks "$100,000 in punitive damages". Washington State does not allow for punitive damages in its courts. Only cases heard in Federal Court are eligible for punitive damages in the State of Washington. Further, Daphne never entered a contract in the first place.
Although Mel would probably be none the wiser, calling Daphne a 'Cockney Tart' would be abhorrent to Daphne as she is from Manchester, a Mancunian, not a London cockney.
After the process server serves Daphne, he leaves Frasier's apartment by going around the hallway to the right. Which makes no sense since we know the elevator is directly facing Frasier's door. However, it was established earlier in the show that a stairwell is around the corner, so it makes sense he would choose that to make a speedier exit than simply turn around and wait for the elevator, to avoid a possible confrontation with Daphne or someone else over her being served.
(At 00:01:26) When Niles drives over the speed bumps in the Winnebago, the actors just bounce in their seats. The whole Winnebago should move up and down, not just the actors.