This is one I caught long ago when it first aired. In the episode 48, "Glitter Rock" (4-12-74 leap date), there is a slip up. One scene outside of a concert hall at night, the camera is panning across the building, cars are pulling up and dropping people off in front of the building and then you'll notice something strange. Parked in front of the hall is a red later model 1980's Ford Mustang. Clearly this is impossible and a mistake due to the leap date of 1974.

Jason Kassis

Pekin, Il.