Continuity mistake: When Gertie places a pot of wilting flowers onto the Radio Flyer wagon, an 'enter' sign can be seen on Elliott's bedroom door with a handwritten paper saying 'do not' taped upon it. After she knocks, Mike opens the door to let her in - but the 'do not' paper is now tucked behind the 'enter' sign instead. (00:37:00)
Continuity mistake: When Mary gets her first look at an ailing E.T. lying on the bathroom floor, she panics then hurries everyone downstairs - leaving E.T. behind. Moments later one of the astronauts happens upon E.T. and now a bright pink bath towel can be seen draped over the bathtub's edge, which wasn't even there to begin with. (01:16:00 - 01:17:55)
Continuity mistake: In the scene on Trick-or-Treat night, Elliot and E.T. go to the forest so that E.T. can set up his communication device to "phone home". While they are there, Elliot is appealing to E.T. for him to stay, saying he will get used to it. While he is talking to E.T. he is inches away from his face. But in the very next shot it shows E.T. looking around, staring into space, with Elliot nowhere to be seen. But the next shot shows Elliot is in E.T.'s face again just as he was two shots before.
Continuity mistake: Throughout the movie E.T.'s fingers are shown to be very long, thin, and boney. But in the final scene, when Elliot and E.T. are saying goodbye, E.T. reaches down to pick up the flower pot to take with him. The camera shows his hands picking up the flower pot but they appear the size of human hands wearing gloves, not the long skinny fingered hands we saw during the entire movie.
Continuity mistake: When E.T. is in the kitchen reading comics, he glances over at the TV then takes a look at the coffee table which has, among other items scattered on top, six pack rings. A few shots later E.T. is at the coffee table working to create a communication device, but now there's one can of beer attached to the rings. (00:48:05)
Continuity mistake: When ET is walking with Elliot and his brother trick-or-treating, we see several shots from ET's point of view of people walking toward him. In all of the following shots however, none of the people that were walking toward him can now be seen behind him as they should be. It's not a montage either, these scenes are to be taken that they are occurring in real time.