Just before Niles proposes to Daphne, Frasier goes to hide behind the staircase and the handrail wobbles.
As Frasier tackles the trumpet player after Niles proposes, the padded mat for both actors to fall into is briefly visible on the floor.
Frasier and Niles, despite their knowledge of food and restaurant trends, are surprisingly unaware of blackened Cajun food, which was popular in the 1980s and 1990s. Considering their meticulous planning of the event, and Niles's allergies, it is also difficult to believe that they would be unaware of this, or any, detail of the menu.