Goofs

The cast's hairstyles, and the color of the socks change from scene to scene due to the sporadic four-year shoot.

When Derek falls off the cliff, you can see one of his shoes fall off. In the next shot when he hits the ground both shoes are on his feet.

Derek wipes some blood off his glasses and smears it further, the next shot shows his glassed perfectly clean again.

Several aliens are seen being killed numerous times. The two aliens playing patty-cake are seen dying at least four times each (both of them during two same scenes). The first alien shot at the beginning of the gun fight also falls from the tree.

The team member talking on the car's CB radio starts out holding the microphone handset backwards.

When Derek closes the flap of his skull the second time just before he ties his belt around his head, his hands are upside-down. If he were reaching around to the back of his own head his thumbs would be on the bottom. They are on the top.

When the boys are getting kitted up in the forest to rescue Giles, even though there's supposed to be nobody for miles, through the trees in the background you can clearly see cars driving along a busy road.

When Frank is in the middle of the field being shot at by the aliens in the tree, the wires controlling the squibs are visible.

When the "chef alien" is fighting with Ozzy outside, in one shot, a baby-blue cloth, which may be a pillow, can be seen sticking out at the bottom of the chef's shirt.

When the sledgehammered alien falls to the floor, you can see a black pad he's wearing and a white hose - which runs up his shirt - used to pump out the blood.

During the vomit-eating scene, the camera pans over the staircase and it casts a shadow over the banister.

When Derek hits the rocks, you can see a crew member throw a bucket of blood, and you can see two hands throw the legs over the rocks. You have to use slow motion to see.

When Derek is holding on to the rope off the cliff, there is a visible crew member in black in the top left near the bushes

When Derek kills the "stupid" alien by pushing the gun through the stomach, the cameraman is reflected in Derek's glasses in some shots.

As Derek leaps through the hole in the ceiling towards the alien leader, a crew member can be seen standing above him on the left hand side of the hole.

When the boys see the aliens in their true form, they become surprised and Barry says "Derek was right all along." Even though the boys know that they're aliens anyway.