Kelso is seen eating eggs, but his egg allergy is a major plot point of the earlier episode, "The Kids Are Alright" (s6e1).
The wall sconce in the kitchen is upside down throughout this entire episode.
When Hyde is talking to Donna, he steps back from his El Camino. When he does, the carburetor is visible. It is prominently branded "Edelbrock". Edelbrock did not make this style of carburetor in the 1970s or early 1980s.