Continuity mistake: When Kitty comes downstairs to give the gang cookies, she tells Eric that she picked out an outfit for him to wear on career day. He then turns and mouths the words "Help me." In the next shot you can see Jackie sitting on Kelso's lap when in the previous episode, she broke up with him. In the next shot she is standing behind him. (00:01:00)
Visible crew/equipment: In the scene in Bargain Bob's where Donna is talking to Bob, the end of the set and lights can be seen in the reflection of metal cookware that Bob is tying balloons to. (00:07:50)
Punk Chick - S1-E22
Other mistake: Jackie and Kitty are baking a pie in the kitchen and Kelso walks in. Jackie and Kelso have an awkward encounter as if they are separated, but they got back together at prom.
Thanksgiving - S1-E9
Factual error: The scene where Kitty is making peanut butter celery for Thanksgiving appetizers; she is using Skippy brand peanut butter and the packaging is not from the 70's, it's the current packaging. (00:05:10 - 00:06:05)
Continuity mistake: When Eric is at the pharmacy, Bob picks up a bottle of cologne. When the shot switches so does the bottle of cologne.
Punk Chick - S1-E22
Continuity mistake: When Eric and Hyde are talking, while on Hyde's front porch, they talk about painting a pot leaf on the Water Tower before Hyde leaves to New York, but they already did it in the previous episode, "The Water Tower." (00:17:35)
Factual error: Boxes of Krispy Kreme doughnuts are seen in several episodes; there were no Krispy Kreme locations in Wisconsin until after 2000.
Continuity mistake: In the scene where Donna, Kelso, Eric, and Hyde are in The Hub after Eric Gets Suspended, Donna gets mad at the guys and leaves. But two shots later when Hyde is seen smiling and sipping his soda, you can see Donna's hair on the left side of the shot as if she was still sitting where she was before. (00:03:00)
Donna and Eric Sleepover - S2-E8
Continuity mistake: The design of Forman's Spider-Man sheets are of the Spider-Man from the late 1990's cartoon.
Factual error: In the intro theme, most of the cars in the background are newer then the set time period. About halfway, you see an at least 1997 Ford F-150 pickup drive by the left windows, not manufactured yet.
Punk Chick - S1-E22
Revealing mistake: While cuddling in the car Donna tells her boyfriend that she isn't wearing a bra when it is obvious that she is - at one stage when she leans toward him her sweater tightens across her back and the shoulder strap and clasp of her bra is outlined.

Visible crew/equipment: When Jackie tells Eric that she can really use a friend right now, in the next shot facing Eric just as he says, "Okay, well, good luck with that," the camera and crew member wearing a blue shirt can be seen at the left side of the screen. (00:01:00)
Factual error: When Mrs. Foreman gives Fez and Hyde Snack-Packs after they are caught trying to steal beer, they are in clear plastic containers. From 1968-1984, Snack Packs were in cardboard containers with a tin bottom and a tin pop top. From 1984-1990 they were in plastic containers, but not clear ones. It was not until 1990 that Hunts introduced the clear plastic containers.
Who Are You - S6-E15
Factual error: In this episode, when Donna and Jackie are arguing about who is going to go outside, Jackie is seen holding a box of Chips Ahoy cookies. The logo seen on the box was used in the late 90s and early 2000s, rather that the logo used in the 1970s. (00:17:30)
Prom Night - S1-E19
Factual error: In the scene where Kitty and Midge are talking about work there is a box of Krispy Kreme doughnuts on the counter. The logo that is on the box was not used on Krispy Kreme boxes until the mid 80's.
Let's Spend the Night Together - S7-E2
Factual error: After Kelso gets the call that his girlfriend's water had broken and runs out of the room, Fez answers the phone. In the background there are several license plates on the wall, one of which is an Indiana "Amber Waves of Grain" design, which was first issued in 1993.
Everybody Loves Casey - S4-E26
Factual error: The gang keeps referring to the theme park 'Great America' as "Six Flags." Up until the 80's the park was actually Marriott's Great America. There is no other Six Flags theme park in the area. - from Wikipedia "Marriott Corporation began construction on the park in 1974, and opened it in 1976 as "Marriott's Great America". In 1984, the park was purchased by Six Flags Corporation, becoming the 7th Six Flags park."
Continuity mistake: At the end of the episode "You Shook Me", Jackie is talking to a drunk Kitty who is putting mini umbrellas in Jackie's hair. The first shot of her doing this, she puts a green umbrella on the right side of Jackie's head. After Kitty asks for more umbrellas, the shot changes to Jackie which now has a pinkish, red umbrella on the right side and two green ones on the top.
Mother's Little Helper - S7-E7
Continuity mistake: When Kitty is showing Red "The Joy Of Sex" in the kitchen, the book goes from open to shut instantly between shots.
Factual error: A map of Canada appears behind the guys as they're being questioned by the Mounties. The territory of Nunavut, which was not officially drawn until the year 2000, appears on the map. It definitely did not exist in 1978. (00:18:45)
Chosen answer: He isn't. Time moves slowly in the show because they didn't want it to turn into "That '80's Show". In the first episode, he say's he's 17 but the second episode was his 17th birthday so he must have been 16. The first 12 episodes are set in 1976, the next 2 seasons are set in 1977, the next 3 seasons are set in 1978, and the remaining shows take place in 1979 with the final show on Dec 31, 1979 when Eric must be 20 as he turned 17 in 1976.
Myridon