Continuity mistake: When the Antereans go into the sea for about the second time I think, Jack stays on the boat and starts playing about with the machine and makes it go off. When it does he drops a load of sweets or nuts out of the bag he was holding, but when the camera cuts away then cuts back there are no nuts or sweets on the floor.
Continuity mistake: Tawnee Welch massages Steve Guttenberg's right leg just after he bangs it. However, when they are talking his left leg mysteriously becomes the injured one.
Factual error: Young David focuses his telescope at the moon. A close up shot then shows a circular view i.e. it is supposed to be the view through the telescope. Both the moon and the clouds in focus. With a telescope the depth of field is short and, with the moon in focus, the clouds would actually be blurred.
Deliberate mistake: David spots the boat with the old folk on and runs around the harbor, down the jetty and jumps towards the dive boat as it leaves the jetty. He doesn't jump very high and you can see he would miss the rail on the boat. In the next shot, a (larger) stunt double is shown leaping high in the air onto the boat and, of course, catches the rail.
Audio problem: When Ben and the rest of his friends are "out on the town", he starts his car to go home, but when he does it makes the distinct sound of an older Chrysler when he was driving a Cadillac.
Continuity mistake: Water in the pool becomes instantly still after the old men get out the first time.
Continuity mistake: David goes with his Grandpa when the old man has his eyes tested. David's hairstyle changes from shot to shot. He starts with a center parting and then has a more dishevelled style.
Audio problem: During the dancing scene at the "hip young person dance bar," there are shots of people commenting about the old people dancing. In every shot with people commenting on the older people, none of their mouths are moving to what is being said.
Continuity mistake: When the men are in the pool and the aliens are coming, they run and hide, leaving behind 2 chairs in the pool, but when the aliens get to the pool, the chairs are gone.
Continuity mistake: When Jack first finds out the people on his boat are very strange, he jumps overboard. One of the alien men throws him a lifesaver ring, but where it ends up nobody knows - it disappears.
Continuity mistake: When the eggs are first seen in the pool, there are 4 of them, but when the men leave, there are 6.
Other mistake: Rose has supposedly passed away but her chin moves (in a swallowing motion) as Bernie is trying to wake her.
Revealing mistake: Don Ameche's double is the one doing the elaborate dancing on the floor at the bar. You'll notice the double's hair is different and if you slow the scene down, it's clear it isn't the real actor.
Visible crew/equipment: Near the end when the Coast Guard is chasing the boat, there is a shot looking at Wilford Brimley. The perfect shadow of the camera can be seen since the light is directly behind the operator.
Revealing mistake: When the Pillsbury alien comes in to the pool house, a bright white light turns on from the far left. It is supposed to be emanating from Pillsbury. The color is also incorrect.
Other mistake: When the 4 humans rush out of the pool house, there are 3 aliens not dressed in their human skins watching them leave. The problem is: only one alien has eyes. We've seen the aliens out of their skins heaps of times and they always have eyes.
