In the credits, Doug Spinuzza is credited with the character name of "Barney," yet, when he is seen in onscreen (in Jeff's office talking with him, Daniel, and Ken), Jeff calls him Frank several times.
When Lindsay is sitting on the couch talking to Millie, the position of Lindsay's blanket changes between shots.
Lindsay grabs the volume of the encyclopedia labeled "M", but turns to the back of the volume to find marijuana. This is because the encyclopedia volumes have clearly been relabeled as simply A-Z. The real volume 16 published by Funk & Wagnalls reads "LAW-MARIN", making it appropriate that Lindsay has to look in the back of the book.
Kate Jackson left Charlie's Angles in 1979 yet we see the Weirs watch a prime time episode with her in it in the spring of 1981.
Lindsay rolls a joint on the album cover of "Ghosts in the Machine" by The Police. This episode takes place in the spring of 1981 yet "Ghost in the Machine" wouldn't be released until October of that year.
This show is supposed to be around 1980. But, at the end of the episode, the kids are all dressed up for the sci-fi convention. Sam is obviously supposed to be Luke Skywalker from Star Wars: Episode IV - A New Hope (1977), but his lightsaber prop is the one used by Ewan McGregor in Star Wars: Episode I - The Phantom Menace (1999) which came out about 19 years later.
Nick talks about eating Drake's Cakes. At the time (1980), Drake's Cakes were an East Coast product and not available in Michigan.
When Lindsay is reading about marijuana in the "M" encyclopedia, she is looking at the end of the book instead of the beginning. Marijuana would be in the beginning of the encyclopedia since the second letter is "a".