When Telly is running away from NSAgents for the first time, she runs into the store and we see a shop assistant standing behind the cash desk. In the next shoot, when the NSAgent runs into the store, there is not only the man but also a girl behind a cash desk - she wasn't there in the first shoot.
Before Telly starts tearing away the wallpaper in Ash's office we see a framed Hockey Jersey and five smaller framed pictures on the wall hanging over a desk. When she starts cutting the paper everything is still there, but the desk has been moved. Then when we pull back the only thing left is three small picture frames; everything else has disappeared.
When Ash smashes a large window to exit from the house on Long Island, after the glass has shattered and fallen, there is still glass along the top of the frame as Ash and Telly start to walk through the frame. However, when the shot cuts to outside, we see them stepping through the frame and there is no more glass along the top of the frame.
When Telly is in Ash's apartment for the first time Ash takes a drink from a glass. There is some liquor left in the glass but when he turns and places it on the counter to refill it, the glass is empty.
At the beginning of the movie, when Telly first visits Dr Munce and thinks she had a cup of coffee when she came in, Dr. Munce has a dark (green?) coffee cup on the table next to him. When he picks it up, it's white. Then later it's a green one again.
The address for the house on Long Island that is given is only the street address and "Long Island." In actuality, Long Island is made up of many smaller towns and different counties. There should have been the name of a certain town included in the address, otherwise the house could have been located anywhere on the whole island.
After the alien's attempt to make Telly forget her son fail, he is taken and everything is returned to normal in which the kids have returned to the world along with Ash Corell after he was taken. Anne Pope was taken as well yet her fate is left unknown.
Telly manages to encounter her husband again after disappearing with Ash yet he does not seem to remember her at all. This is an issue that is never addressed in the film again. In fact this character is never seen again after this sequence.