When Ernest and the elves are orbiting the Earth in the sleigh, the picture of the Earth shows that it's daytime in the Western Hemisphere, but Ernest's sleigh ride took place at night.
Right after Santa Claus tells Ernest that he doesn't have money, the clothing that the girl is wearing changes.
At the very beginning of the movie, the plane that lands is a 2-engine DC-9 (or possibly an MD-80, an updated version of a DC-9). But the plane at the gate is a 3-engine Lockheed L-1011 TriStar.
When Ernest is driving the sleigh, right before the shot of the FTD billboard ad, the elves in the back seat disappear for one shot.
The "power-up" lights of one of the reindeer turns on before its name is called.
In the puppet-show scene when Joe is first seen, he is using dinosaurs as his show's theme. He proceeds to narrate how dinosaurs got sick and died because of an ice age--an unfortunately common misconception. In fact, dinosaurs became extinct after a huge meteor crashed into Earth about 65 million years ago.
When Ernest arrives on the sleigh, the lady with Santa starts to brush away the snow before it starts flying around her head.
At beginning of the movie when Ernest is taking the first guy to the airport and he jumps the bump in the road sparks fly from underneath the car even though he has not touched the pavement.
For the "Aster Clement" sequence, Harmony is able to change her hairstyle back and forth too quickly. Braids can not be done and undone that fast, especially since she would have been doing her hair by herself.
When Ernest gets into a multi car crash on the interstate (for save a Christmas tree), one of the cars speeds backwards.
When Ernest arrives at the airport, his car catches air, but look closely at the sparks and it is actually a grind rail.
Marty's car has a license plate mounted to the front. Florida only requires rear license plate mounting.
When Earnest and Harmony arrive at Vern's house for the Christmas party, Harmony says "Well I hope he's got something I can eat, not just a lot of things made out of white sugar and red meat." In the next scene at Vern's house, Harmony seems interested when Vern put out some bacon cheeseburgers.
Santa Claus keeps claiming that he really is Santa Claus. He also goes to jail for insanity of saying he's Santa Claus. But near the end when he introduces himself to Mary Morrissey, his real name is Seth Applegate. The mess and the chaos, all could have been avoided if he just used his real name in the first place especially to the police. There might be a chance that Seth might have forgotten all about his real name because he loved doing the job for so long.
Ernest gets in trouble for allowing Santa a free ride, but not for doing the same for Pamela, who never pays for her own trip. She even mocks Ernest for not having Santa arrested, conveniently ignoring that based on her rather more serious claim of having been enslaved and abused by her uncle, he should have called the police for her sake as well.
Bobby tells Ernest they are saving the reindeer for sum one named helper elves and they have some Good questions for whoever that is yet when the elves arrive they don't ask them one single question.
Pamela doesn't believe that Seth is Santa Claus, despite the fact that he clearly flew on a plane and landed in Orlando. Plane tickets are not cheap. He couldn't be homeless and afford this. Yet through a good majority of the movie, she believes him to be a homeless man. Ernest could have simply told her that he came off of a plane from the Orlando airport and would have stopped this very quickly. This just wouldn't happen.
Anyone can take a taxi from the airport without ever having been on a flight, just as if they were in front of any other building. In any case, flying on a plane isn't definitive proof a person is Santa Claus - that would imply a rather huge and year-round population of Santas. Nor is being able to afford a commercial flight. Even homeless people are able to ride on planes, either with the help of friends or charities, some sort of lucky draw, or even paying for themselves. A one-time plane ride is a good deal more affordable than regular housing.
Anyone can take a taxi from the airport without ever having been on a flight, just as if they were in front of any other building. In any case, flying on a plane isn't definitive proof a person is Santa Claus - that would imply a rather huge and year-round population of Santas. Nor is being able to afford a commercial flight. Even homeless people are able to ride on planes, either with the help of friends or charities, some sort of lucky draw, or even paying for themselves. A one-time plane ride is a good deal more affordable than regular housing.