Continuity mistake: When Barry is getting followed across the beach by the guy, Barry shoots him once and blood falls on to the floor, and also on to Barry's face. He shoots the guy a second time in the head, and the view is from behind as the guys head explodes. If you look at Barry during this shot, you'll see his face is clean of any blood once there, but then it returns in the next shot.
Continuity mistake: When the guys are in the forest clearing, getting guns from the car boot and changing their clothes, Frank says "Don't you forget Oz..." and he takes his white jacket off while he is speaking. But in the following shot Frank's jacket is now back on him again, zipped all the way up.
Continuity mistake: In the scene where the guys are getting the weapons from the car, in the forest clearing, the ground surrounding the parked car changes through the scene. At first, it is brown dirt with branches and twigs everywhere. By the end of the scene, when they exclaim "the bastards have landed," the ground is now covered with lush green grass.
Continuity mistake: When the guys are in the room eavesdropping on what the alien leader has to say, one alien holding a glass bowl walks in on them. In this shot, Frank's wolleen hat is off. Then in the shot when Frank punches the alien, it has reappeared back on his head. Cut back and it has gone again.
Continuity mistake: During the shootout in the gardens, Frank is standing by a large green plant, which is in the middle of the gardens, with grounds, plants and paths behind it. In the next shot as he runs to the next plant, running behind the previous plant is a small wooden fence, which has suddenly appeared.