The spider was stored in the high school auditorium. When it revives and goes through the downtown area, it is as big as a two-story building.
The spider awakens and scares the kids at the band practice in the school. The drummer looks up in horror and flees his drum kit. In the following wide shot , the drummer is back to playing his drums again.
When a citizen is fleeing from town and sees the spider return to the cave it is dark. The next scene back in town seen from the Sheriffs office it is clearly still daytime.
When Mike and Carol are exchanging notes, Carol takes the paper and can clearly be seen to write three separate lines of text (ie: she returns to the left-hand margin and begins writing three times), yet when Mike looks at what she's written, it is shown as only two lines.
The spider expert repeatedly refers to them as insects.
When the young couple find skeletons in the cave,the bones are all connected together. Without muscles or skin, they would look like a random pile of bones, even if they were in the same area.
The word "starring" is misspelled (as "starrring") in the opening credits.
Although the spider's web plays a large role in the story, tarantulas don't spin webs.
Several skeletons in the cave are perfectly clean and bleached white, but George Weston's skeleton is dirty and covered in cob webs. Also, all of the skeletons are completely bare, as if they all died naked. No hair, no skin, no clothes.
The exterminators lay down a spray of 50 percent DDT to flood the entire cavern, yet only bring enough gas masks for half the people in the cave.
The so-called teenagers look more like post-graduate students than high schoolers. Skip Young, who was also a regular on "The Adventures of Ozzie and Harriet," was 28 and Tony Patterson, who played "Joe," was 35 years old.
In all scenes the spider is seen as black. In one scene where the spider is approaching the house of the main character, it is light-colored or gray.
In one shot of the spider walking past the main street of the town, the lower part of its legs aren't seen touching the ground, because of a poor matte effect.
The web is obviously made of rope and looks more like a cargo net, as it's not woven in anything resembling the pattern of an actual spider's web.
Carol gets out of the car to look for her missing father. As she gets out of the passenger side door you can see the film crew and movie camera reflected in the car's black paint.
When Mike and Carol search for her Dad, they are traveling on a dirt road, the next shot is a close-up in the car and in the background they are now traveling on a lined asphalt road.
Professor Kingman tells the Sheriff that, even dead, the spider needs to be studied so that scientists can learn why it grew so large and so prevent a race of giant spiders from enslaving Earth...a supposedly key plot element is never mentioned or dealt with again.
Human skeletons litter the cave. Nobody cares about identifying any of the remains.