On the TV show Growing Pains, they had an infant daughter who suddenly aged 4 years between seasons. Gave them the advantage of having a “cute kid” character when the novelty of the baby wore off.
I was surprised to learn that Donna from That 70s Show had not 1 but 2 missing sisters.
As Cecil points out, the hubcaps on Steve McQueens Mustang spontaneously regenerate several times during the chase scene in “Bullett.”
Judy Garland’s shoes change back and forth between ruby slippers and plain, black shoes several times in TWOO.
Res, they did that one Family Ties too.
They also send off children to boarding schools in various soap operas, and in a few months, they’ve become teenagers or young adults.
I think some sitcoms are getting away from that…Ben (Ross’s son) on Friends seems to be aging normally.
Oh, I forgot: Han Solo’s infamous disappearing vest in The Empire Strikes Back.
Ruth McDevitt’s character in Kolchak: The Nightstalker keeps changing identities and jobs.
One I picked up on just recently was from The Andy Griffith Show. In the very first episode, Barney is said to have gotten the job of deputy only because he is Andy’s cousin. However, in a later episode Andy mentions how many years he and Barney have been friends. No mention is made of their being cousins! 
How about in Star Wars when they’re flying down the trench… Darth Vader has the rebels in his sights, then they cut to a shot from the front of the rebels, and behind them there are no tie fighters?
In “Raiders of the Lost Ark” in the scene in Marion’s bar right before the Nazis show up, the headpiece to the staff of Ra is on a chain around her neck. She hangs it up on something without taking the chain off her neck.
Yeah? Well, at least my man Bart isn’t 13 years old and still crawling around on the floor sucking a pacifier, unlike certain sisters of his I could name!
About The Andy Griffith Show - maybe that’s a symptom of something that’s still common in TV today: pilot episodes are used to “sell” a show to a network, and thus they are often filmed well before production on a series starts. As a result, sometimes story details aren’t fully hammered out in the pilot, and it doesn’t quite match the rest of the series.
Another example of this: in the pilot episode of The Cosby Show, Claire asks Cliff, “Why do we have four children?” Cliff answers, “Because we didn’t want five.” Contrary to their exchange, oldest daughter and fifth child Sondra is introduced later in the series
There’s an infamous scene in Girl in Gold Boots where one of the main characters suddenly appears in a diner with the other two. No break in the conversation at all, one second he’s not there, the next he’s teleported in.
The son on Frasier seems to be aging normally too.
But off the top of my head i can think of two shows that have pulled the infant-teen in a few weeks thing.
Stargate sg-1 used nano-machines to explain it,and on Angel i guess time just passes more quickly in hell dimensions,well at least from our perspective.
The best example of what Stephen King calls the “Kid Trick” was on Days of our Lives. Belle Black was a flower girl at her parent’s wedding, and when they came back from an apparently very very long honeymoon, she was a junior in high school.
And of course All My Children had Bobby Martin, who went upstairs to polish his skis and was never seen again.
Not really a continuity error, but I watched Days of our Lives for 10 years and nobody ever mentioned the Brady family. Then Roman Brady was brought in to protect Marla from a stalker, and the next thing I knew there were about 9,742 Bradys, all with a very long past in Salem. Where were they all those years?
Ever notice how soap opera characters disappear for years and nobody even mentions them, then suddenly 12 people mention them in two days and the next day they show up?
I thought of another one from Star Trek Undiscovered Country.
At the beginning, Sulu is captain of the Excelsior, coming back from a mission of cataloging gaseous anomolies. They witness the explosion of Praxus.
Toward the end, while theEnterprise is trying to blow up the Klingon vessel that can fire while cloaked, Spock mentions gas, and that although they can’t see the ship, it still discharges gas.
Uhura mentions all that equipment they have on board to track gaseous anomolies, and why can’t they use that.
Did the Excelsior transfer their tracking equipment to the Enterprise and I just missed it during the 50+ times I’ve seen the movie?
My favorite flub is from the James Bond flick, Diamonds Are Forever, when Bond (Sean Connery, in this case) and some lovely young woman (possibly Jill St. John, won’t swear to it being her in this scene though) are being chased by the bad guys. Bond is driving in an alley, apparently caught since up ahead there is only a narrow space between two buildings. Fortunately, Bond sees a ramp for a loading dock, and steers so the two left wheels go up the ramp, getting the car driving only on the two right wheels, and narrows the space the car is taking up enough to fit between the buildings.
We then cut to the next shot of the car coming out from between the buildings – only now, the car is on the two left wheels.
I just saw the episode where Donna on the 70’s Show is watching her younger sister. I had forgotten that episode. Where is the second sister?
It is weird too because though they never mention Eric’s sister anymore, she was older and easily explained why she’s never around.
But at least ONE of Donna’s sisters was younger. Where was she when the marriage broke up?
Hanging Out With Chuck (that would be a great name for a website)
In Arnold Schwarzenegger’s “Commando,” keep an eye on that yellow convertible. After its initial crash, SOMETIMES the car’s left side is all smashed up, and sometimes it looks as good as new.
Incidentally, since plnnr mentioned Steve McQueen’s “Bullitt,” how about that green VW Beetle that McQueen passes about half a dozen times, during a supposedly high-speed chase.
Funny how the more you read this thread, the more you remember.
A Knight’s Tale: William is in the barn trying to learn how to dance. Geoffrey is counting off the beats. He says something smart, and the redheaded guy decks him.
Next scene, we see a bit of cloth stuffed up one of Geoffrey’s nostrils, presumably to stop the bleeding.
The female blacksmith comes in, and the next shot of Geoffrey’s face shows that the cloth has moved to the other nostril.