After Dan hangs up the phone with his ex-wife in the start of the movie the police officer uses the phone and if you listen carefully you can hear "if you need help hang up and dial your operator," and it still happens as the officer dials.
During the "test" on "Little" Buddy, after the family has all been killed the camera switches angles from an in room shot to a monitor shot. In these shots it's clear "Little" Buddy's legs have changed their position several times.
Ellie and Rafferty stand outside the hotel while Dan goes to check in. The sunlight is seen brightly shining on the windows of the hotel as Rafferty draws attention to Mr. Cochran's car. The scene cuts to an interior shot of Rafferty and Ellie as seen from Mr.Cochran's point of view inside the car. Looking at the windows of the hotel it's obvious the sun is at a different position from where it was just a moment before and the light of day has faded.
As Ellie Grimbridge meets and talks to Marge Guttman outside the motel: Ellie's jacket is open. In the following shot when Marge shows Ellie the displaced Silver Shamrock trademark, her jacket is nearly closed. Yet, in the next shot, Ellie's jacket is once again open.
When Cochran gives Challis a demonstration of the Halloween mask on the Kupfers while they are in test room A, the closed circuit TV behind them in the final processing area shows Betty leaning into Buddy Sr. as the special Silver Shamrock commercial starts. When the next scene cuts into the test room, Betty is resting her chin in her hand and the shot plays out seconds later. As little Buddy is bent over the TV staring at the "Magic Pumpkin" with the mask on, Betty mentions how everything "is a big joke". When the scene cuts back to Cochran, Challis and the robot humanoids again, the closed circuit TV shows little Buddy standing up straight with the mask in his hands.
When the children are seen from different cities buying or wearing the Silver Shamrock Halloween masks the child on the bicycle in Omaha, Nebraska passes by a business called "Landis Dept. Store". It was a general store actually located in Los Angeles, California that closed its doors eight years after the movie was released.
When the process of making masks is explained. It is said that the latex is heated and poured. If they are using liquid latex to make the masks then no heating is necessary. If they are making foamed latex (although the masks just seemed to be regular latex) then baking would be used once the foamed latex is poured but not before.
When Challis calls his ex-wife from the hospital on Saturday, October 23rd he dials eight numbers. When he calls her on Halloween night from the unrestricted phone in the Silver Shamrock storage room, he dials six numbers: 625418.
In what appears to be at least an hour or so after curfew is put in effect, Challis goes to a liquor store. Even if he didn't know about the curfew, it is not explained why the liquor store would still be open.
Just like on October 29th when Challis and Ellie initially booked a room at the Rose of Shannon Motel in Santa Mira, on 7:30PM Halloween night the liquor store in town is still open past the 6PM curfew.