Continuity mistake: When Charlie Brown is doing the dog food for Snoopy, the amount of food in Snoopy's dish changes between the kitchen and the dog house.
Revealing mistake: Near the end of the film, Charlie Brown, Linus and Snoopy all cast shadows from the moon, and then suddenly seconds later all the shadows are fully gone. Also, no shadows were cast from any other object around them when the shadows were shown on the characters.
Continuity mistake: The lampshade by Charlie Brown's bed changes throughout the film. First it's just a blank shade with nothing on it, then near the end of the film it has two boats printed on it. On the boats there are orange flags on top that first face each other, then change suddenly to both facing the same direction.
Continuity mistake: When Charlie Brown arrives at his hotel room, the door handle does not have a keyhole on it, yet a keyhole appears when both Linus and Snoopy arrive to see him.
Continuity mistake: Before Charlie Brown is about to leave on the bus for the spelling bee competition, you can see that he is holding a rucksack and there is a suitcase next to him. When Linus comes up to him and tells him to get aboard the bus, the suitcase is nowhere to be seen.
Continuity mistake: When Lucy is writing the numbers on the piece of paper when she is at the desk, you can see she puts the pen on the paper when she says "Lucy Van Pelt Inc", but in the next shot the pen is back in its holder.
Continuity mistake: After Linus wins the game of noughts and crosses with Charlie Brown, he puts down his stick and leaves. When we see Charlie Brown in the next shot, both his and Linus's stick have moved positions.
Continuity mistake: When Charlie Brown's friends are watching the spelling bee on television, you can see that Lucy is not sitting on the chair when Violet says "That's an easy one!", but when the gang say "Agh!" after Charlie Brown lost, Lucy is back on the chair again.
Continuity mistake: When Linus is in Charlie's bedroom towards the end of the film, you can see there is nothing next to the side of Charlie's bed, but when Linus leaves the room, Charlie's shoes and a sock have appeared.
Continuity mistake: When Linus and Snoopy enter the theatre where the spelling bee is taking place, you can see they are entering from the interior of the building, but when Linus tells the usher he's a friend of one of the contestants, they are shown going inside from the exterior.
Continuity mistake: Lucy gives Snoopy Charlie's red kite and he flies it. After a quick cut to Charlie, we return to Snoopy, and the kite he is flying is now yellow.
Continuity mistake: When Charlie is looking out of the window when he is on the bus with Linus and Snoopy, the bus passes the same garage three times.
Continuity mistake: When Charlie, Linus and Snoopy enter the bus at the Depot, Charlie goes to his seat and you can see he is sitting near the arm rail, but when the bus starts moving he is now sitting near the window.
Continuity mistake: When Charlie, Linus and Snoopy leave the Spelling Bee after Charlie lost, you can see they have nothing on their heads, but before they enter the coach at the Depot, they are all wearing hats.
Continuity mistake: When Charlie's friends are watching the spelling bee on television, Violet says, "Atta boy, Charlie Brown, you can do it!", but in the very next shot Violet has disappeared.
