Revealing: Joe is much too old to be in high school. He appears to be in his thirties (the actor playing him was 35 at the time).
Great sites
Mistakes
When the old man who left town sees the spider return to the cave, it is dark outside. He returns to town to report, and it is daylight outside. The sheriff and his men leave immediately, but when they get to the cave it is dark outside once more. The cave is not so far from town that it takes a day to travel the distance. See more...
Earth vs. the Spider mistakes
Revealing: When the spider is being electrocuted and falls off the cave wall, you can easily see the string that was holding it.
Continuity: When the old man who left town sees the spider return to the cave, it is dark outside. He returns to town to report, and it is daylight outside. The sheriff and his men leave immediately, but when they get to the cave it is dark outside once more. The cave is not so far from town that it takes a day to travel the distance.