In Beloved Infidel (1993), Frasier (Kelsey Grammer) cannot understand the caller (JoBeth Williams) who is French. It is later revealed that Frasier speaks French fluently when passing notes to Niles (David Hyde Pierce) in this episode.
The auto mechanics instructor turns the wrench a quarter turn and the spark plug comes out. In reality it takes several full turns to remove spark plugs because they have very fine threads to withstand the tremendous pressure exerted on them.
The engine they are working on is upside down so the heads where the spark plugs that they are trying to remove would be on the bottom and unreachable.
When Frasier removes the topless playing cards from Martin's toolbox, the face of the bottom card can be seen, and it's obvious they are just a normal deck.