During the assault on the town, a white Mustang careens into a parked car. During the wide-angle shot, only the driver is visible. But in the close-up shot after the crash, a female passenger is seen sitting upright in the passenger side just before she crawls out of the wrecked vehicle.
When Rack Hansen and Diane Ashley arrive at Terry's farm, they get out of Rack's truck and close the doors. A moment later when they rush back with Rack's niece, Linda, the truck doors are open.
While inspecting Walt's dead calf, Rack has a sticking plaster on his left thumb which does not appear in any other scene in the film.
At Colby's accident site, the deputy tells the sheriff that an eyewitness was a quarter of a mile behind Colby's truck and saw the accident. However, during earlier wide shots of Colby driving, there was no one as far as the eye could see on the straight highway.
After rescuing Linda from tarantulas swarming around her on the bed in the lodge, Rack recommends that the group leave the lodge, but Terri insists there are too many spiders and they wouldn't make it. Against her advice, he opens the door, which is clear on the outside, but in less than a second, the front of the door is completely covered in tarantulas. There is no reasonable explanation for this.
The radio announcer mentions Prescott, pronouncing it press-cot. However, it is pronounced press-cut. A local, such as a radio announcer, would know that.
The stunt driver who hits Mayor Conner misjudged his speed and hit the brakes just as he made contact. Instead of the car taking out the Mayor and then careening into the water tower, you can see it stop briefly and then accelerate again to get enough speed to take out the water tower.
You can see the "dead" dog on the farm breathing.
When "Rack" gets out of his truck at the scene of "Walter Colby's" crash, a female crew member is reflected in the wing mirror as he opens the door.
Just before his accident, Walter Colby is shown driving his truck. Briefly, a crew member's hand comes into view at the bottom of the screen.
In the recent versions of the film, this has been edited almost completely out.
Shortly after the Baron's crop duster crash, the sheriff has his deputy call Birch Colby at her farm. Meanwhile, Rack and Diane race out to Terry's farm to bring her and Linda into town. However, the mayor had previously ordered the sheriff to move all the outlying residents into town so that the Baron could spray the Malathion. This is especially true of Colby's farm, where the main targets of the insecticide (20 to 30 spider hills) are located.
Diane Ashley mentions a scenario where "the insects will turn on us". As an entomologist she would know spiders are not insects.
When the spiders are overrunning the town and the sheriff is driving his car through the mob of fleeing people banging on the windows, some of them are clearly smiling, and looking far happier than the situation would call for.