When the group enters the TV studio, Cal (the Marine) has his rifle slung over his arm as they close the doors. When they finally close the second door and move into the studio, his rifle is missing for one brief scene. When they finally get inside and Cal introduces himself, his rifle suddenly appears on his shoulder again.
As the group is driving away from the airport, they come across a car that had been attacked by the Slime People. In a close-up you can see a couple of other vehicles parked behind it through the car's window, however in a wide view the car is up against the side of a hill and no other vehicles would have been visible.