- Time zones screw up Conal's plot somewhat. If the final commercial goes off simultaneously, then it'll be midnight on the East Coast, and lots of his targets will be in bed. If it goes off at 9 on each time zone, then someone besides Challis should have managed to make the connection between the commercial and the masks — maybe not by Central Time, but almost certainly by Mountain Time. The ending scene would have taken place long before Challis escapes Cochran's factory. Still, though, Cochran's guaranteed to massacre the children of at least one time zone.
- But the only reason Challis knows exactly what's going on with the masks and the signal is because Cochran's told him. Any parents in other time zones would probably be too frantic and terrified trying to save their children to put two and two together, especially when it comes to something as seemingly innocuous as a television commercial that they've seen about two million times across the past few days. Also, as the 80's Dan episode dealing with the movie suggests - we only see the adverts in one time zone; the others could have been at five, six, seven, or eight dependent upon where they are, and each time zone could have descended into general chaos with no-one thinking or knowing to call other TV stations in other time zones.
- Cochran's whole plan hinges on children all across the country wearing one of three specific types of masks while watching his horror movie marathon. There are far too many variables in this scenario, and each of them seem very unlikely, even on their own:
- Assuming that every kid in America would want to watch tv immediately after trick-or-treating instead of just gorging on candy and/or going to bed.
- Assuming that every kid in America has parents that would allow them to watch R rated horror films.
- Assuming that every kid in America would even want to watch a marathon of horror movies. Yes, kids can handle scary stuff in media better than most people give them credit for, but there are still plenty of kids out there that would be too scared to even try watching a horror movie.
- Assuming that every kid in America would actually buy these masks. As 80's Dan pointed out, a witch, a skull, and a jack-o-lantern are extremely generic, especially with no pre-made costume associated with them. Most kids would far prefer dressing up as their favorite pop-culture figures.
- Assuming that every kid in America wouldn't remove the mask out of eventual discomfort or obstructed vision before the Silver Shamrock jingle started playing.
- Conal Cochran may have considered his "great prank" something of a suicide mission. The police certainly would have eventually traced the havoc and murders back to Silver Shamrock... not to mention his murders of The Kupfers and Mrs. Guttman would have eventually led to the company. Whatever the actual efficacy of the "prank," Silver Shamrock (and probably Santa Mira) would be finished before Thanksgiving.
- Given the timing during the "demonstration" at the factory, the trick-or-treaters at the end were probably starting to die just as Challis' screams "STOP IITTTTT!!" the final time over the phone.
- Even countless nearby kids who did not have Silver Shamrock masks were also certainly killed. Considering the immediately swarm of vermin and vipers released, children investigating or trying to help their friends would have been doomed.
- Buddy's head dissolving into the insects and snakes may have just been one variety of death. Perhaps the Witch and Skull masks would cause other forms of gruesome demise... perhaps even every mask would bring forward a different death.