Niles guesses from Daphne's accent that she is from Manchester and she says he is right. In fact Jane Leeves's assumed accent is not identifiably Mancunian but appears to be a generic Yorkshire.
While they are eating at the restaurant the potato on Frasier's (Kelsey Grammer) plate is there and the next scene it is gone.
After Martin leaves and Frasier and Niles sit back down, you see the waitress walk up to the table behind Frasier. However, the show then cuts to another angle and the waitress is no longer there but she walks in front off camera.
When Niles (David Hyde Pierce) meets Daphne (Jane Leeves) she is folding a black shirt. The position of the shirt changes from being already folded in her hand to being held by the collar and back from shot to shot.