Goofs

When the troll eats the shells from the Sherrif's gun, he only eats about five or six, yet he fires over twice that many.

When Old Lady Hackmore is reading the poem about the troll, she flips the page revealing a stanza she had already read.

When Ernest is thrown into the concession booths at the party, he is covered in ice cream. When he leaves in his truck, he is not covered anymore.

After Trantor has ripped open the roof of Ernests truck, it goes back to being undamaged moments later.

When Ernest leaves there are several bikes outside of the school, yet when Old Lady Hackmore leaves, there is only one bike (the one she takes).

The Ottoman Empire occupied the northern (Mediterranean) region of Africa; Botswana lies in the far south and did not exist as a nation until centuries after the Ottoman wars. Of course, it's entirely possible Ernest made the story up on the spot.

The citizens are seen burying Trantor alive. What they failed to notice is that he has magical powers. He could have easily disappeared and reappeared some where else. They should have instead ripped him to pieces and burned them so he wouldn't be able to come back to life.

There is no reason for anyone in the 19th century to assume a video game solution would have worked or that Trantor, being magical, couldn't magically survive any murder attempt, including dismemberment and fire. In fact, the one spell that works requires someone with a specific kind of personality to succeed at permanently ending him.

The little girl that Trantor the troll is chasing at the beginning of the movie, smiles even though she's supposed to be screaming in terror.

When Ernest's carjack flies into the Mayor's window it is clear that the window breaks before the carjack hits it.

When Ernest picks up the hedge clippers in the back of his truck to attack Trantor, you can see where it is supposed to be sliced off at before Trantor cuts it off.

When Trantor scratches the roof of the truck trying to get to Ernest, you can clearly see that it is cloth ripping instead of the metal on the roof.

While Ernest is falling out of the back of the garbage truck in the beginning, the crew member's leg kicking the block of garbage on top him is visible for an instant.

When Kenny's dad drops Kenny off at the party, you can see a crew member in a ballcap reflected off of the glass.

It's revealed at the end that Old Lady Hackmore had siblings turned by the troll before he was captured the first time. That would make her over 200 years old.

Why would Old Lady Hackmore specifically tell Ernest how to release the troll?

The citizens of modern-day Briarville don't believe in the legend of Trantor the troll except for Old Lady Hackmore, Ernest, and Elizabeth. If he really did kidnap kids and terrorized the town it would have been in the newspaper archives and as a missing persons cold case.

When Kenny and his friends enter the store on the bikes, Jimmy the employee calls Kenny "Kenny Barton" even though he knows that his last name is "Binder" in the film.

Trantor is terrorizing the citizens of Briarville through out the whole movie till the end. He's much stronger and powerful near the end, but when Ernest shows him unconditional love he makes no effort to attack him. He just goes along with the dance.