Factual error: Towards the end Ross pours wine on the egg sac to light it. Wine doesn't contain enough alcohol to ignite.
Suggested correction: He uses cognac and not wine, which is why it burns.
Continuity mistake: When Jerry Manley is shown in the coffin his head is on the right side. When they show the shot inside the hole before inserting the poles, his head is on the left.
Other mistake: The wood coffin that Jerry Manley is placed in has no bottom. Right after showing him in the coffin they seal the top, insert handles and somehow carry him off.
Revealing mistake: At the end when the dock 'kicks' the king spider off him into the fire, we hear it scream like a stuck pig. Then additional screams from the 'burning' spiders inside the pulsating nest, and when the doc torches both the king spider afterwards.
Suggested correction: Not sure how this is a mistake. Sure real world spiders don't making squealing noises but real world spiders also don't jump 30 feet or have venom potent enough to kill a human within seconds of being bitten.
It's a mistake because spiders cannot vocalize at all. The film creates a new spider species with exaggerated aspects of real life spiders: extremely potent venom, highly aggressive behavior, jumping ability, etc. What the film can't do is give the spiders traits they couldn't possibly have in real life.
Revealing mistake: When the flaming "general" spider is killed, there's several mistakes. When it leaps, it suddenly "freezes" in mid-air for a second before the nail hits it. Then, when we see the nail hit it, you can see a wire attached to it, plain as day, to yank it back. Then, when it hits the egg-sack, you can see several fake spiders attached to it, which don't move at all. Then the egg sack catches on fire, but the flames come from behind the sack, even though the general hit the front.
Factual error: The shadow of a spider climbing up the window makes a 'tick'ing sound as it moves, when spiders don't make sounds.
Revealing mistake: Near the end it is way obvious that the king spider is animatronic as it goes for the doctor, considering it's tech string is quite visible in the closeup. And it "hisses" as it's lowered.
Other mistake: When the exterminator steps on the little spider it makes a loud dramatic 'crunch' and then when he lifts his boot the bottom is overcovered in fake brown goo.
Revealing mistake: Two very different types of spiders are used in most of the shots. In the closeups they are larger, with bulbous legs, defined hairs, and big eyes.
Revealing mistake: When Atherton is using his fog machine to spray up into the tree look to his left, you can see another spray of the fog being added to the tree by an unseen stagehand.
Other mistake: The king spider moving up the docs leg at the end is animatronic, considering the way it moves, like a typical Halloween effect. But understandably because it was too risky to use a real one.
Continuity mistake: It's way obvious that the king spider attacking the doc at the end is animatronic or CGI as it's appearance changes. In the far shots the legs are wide spread and it's a purplish color. But in the closeups it's black and half the size.
Other mistake: Near the end when the doctor is pursuing the fake king spider moving along inside the pipes, it makes loud, exaggerated tapping sounds, and then "jumps" out at him from the end pipe and attacks.
Visible crew/equipment: Near the end when the doctor and his family are getting attacked by the spider's, half are CGI and the others fake as you can see the Tech wires making them move. Then when he's lying on the floor collecting himself, there's a pulsating sack in the corner, with a fake spider leg sticking out.
Revealing mistake: When Margaret (the blood pressure lady?) gets settled for the night, one of the baby spiders is crawling toward the couch where she's sitting. In the very next shot that same spider is suddenly 'hiding' inside the lampshade above her and bites her.
Continuity mistake: After Becky's dad comes into the bathroom, and she screams, covering herself with the shower curtain, you can see her brother, who had died at the football game considerably earlier in the movie, through the bathroom's doorway, standing in the hall. It's only for a split-second, but as long as you're looking in the right spot, it's very clear.
