Corrected entry: In the opening scene when they toast Eric stealing something he is holding his beer upside down.
Corrected entry: In the opening scene, the boys are looking at a Playboy centerfold, circa 1976. However, the magazine is perfect bound, not saddle stitched (stapled) as Playboys were at that time.
Correction: It is not a Playboy. It is difficult to read the writing but it is definitely not a Playboy. In a later episode, Hyde is looking at a "Layboy". They didn't use the real magazines. Therefore, since it is "not" a Playboy, the binding is not a mistake.
Correction: Believable character mistake.