Blooper

Barney's father pours rum into his prune juice, twists the cap on and sets the bottle down. Cut to another angle; the rum bottle's in his hand and he repeats his actions.

The gum on Principal Johnson's globe changes position.

The blond-haired member of the Penguin baseball team was seen in the Prom sequence wearing a suit and tie ensemble. Later when Barney used his telekinetic powers to rip his pants off, revealing his Rolling Stones red bikini briefs, he is now wearing a tuxedo.

When in the barrels at the amusement park, Robert's hands change position.

The nerd with the mice says he has given them the human equivalent of ten pints of whiskey for his experiment. Such a large amount of spirits contain several times the lethal dose of alcohol.

Objects in a fish tank are magnified but when a model space ship flies through a fish tank here it appears smaller.

In the baseball game scene, Peyton (Willie Aames) tells Barney (Scott Baio) to wait on using the telekinesis powers until the ninth inning, however high school baseball games are only seven innings.

Barney uses cheese as food for the mice, however it's a fact that constant amounts of cheese is actually bad for mice.

In the close-up of Jane's sweater just before it pops open, you can see that it is buttoned with the left side over the right. When it pops open the buttons stay on the material on the left side of the sweater and there are button holes on the right. The shirt wasn't actually buttoned.

A body double was used in place of Heather Thomas' in the sweater popping scene. You can clearly see dark hair of the double over the front of her shoulders. Thomas is blonde.

Sheldon's voice does not match his lips during the first wide shot at the fraternity gambling party.

When Barney first discovers his ability in the lab, he lifts up a broken piece of glass by looking at it. The black wires used to lift it can be seen clearly when the close-up is occurring. Same thing goes for the dust pan except the wire is clear and it is seen when the wide shot is occurring.

When the ventriloquist dummy rises up from the bed, the crew member's hand is partially visible behind the dummy.

Robert Mandan's character is called "Walter Coolidge" in the film, but during the credits his character is called "Walter Johnson."

Barney's mother calls two Latin & Greek speaking priests to 'exorcise' demons from her son, indicating the family's Catholicism. However, earlier she tried to keep her 'possessed' son away from her by holding up a cross. A Catholic would instead use a crucifix. Which is the same but has an attached sculpture of Jesus' body.