When Roz (Peri Gilpin) returns to the sofa and sits down next to Frasier (Kelsey Grammer) with her glass of champagne, the glass is nearly empty. She sets it down on the coffee table for a moment and when she picks it up again, it is full again even though Frasier has not poured any more.
When Martin is on his stakeout, he takes pictures in dim light at hand-holdable shutter speeds. At best, this is difficult. Even if he could, the high contrast of the lighting (multiple point sources) would make it difficult to get useful detail (especially of the people's faces). Jim Rockford would have used infrared film and flash.
Niles (David Hyde Pierce) has no idea what a tractor pull is, despite taking Martin (John Mahoney) to one in My Fair Frasier (1997).
Frasier remarks that Lilith is dating a member of Cirque du Soleil. Niles refers to the boyfriend as a French circus performer. Cirque du Soleil is a Canadian company centered in Quebec, which is French speaking.