Other mistake: In all the shots of ET wearing the white sheet the two eye holes are about a foot apart, so he could see out of the holes properly, but when Michael finds the white sheet ET had been wearing he lifts the material and we see that the two eye holes are only about two inches apart, which makes no sense. (It was Gertie's sheet which had eye holes that close together).
Other mistake: When ET launches all the bicycles into the air, first there's a closeup of Michael, then in the next closeup of Steve as they climb higher he leans back with his arms outstretched, as if he's balancing himself on his bike, and we see Steve's right hand making a fist pretending to grip his handlebar, though he's not actually gripping anything at all, it's an empty fist. (This shot has nothing to do with CGI disappearing issues).
Other mistake: While ET is pulling the blanket loaded down with small appliances, etc., the TV is playing "Francis Goes to the Races" and when the film's Peter and Frances walk into the stall we hear Frances (the woman, not the mule Francis) say, "Grandpa, what's wrong?" but the subtitles on the DVD (1982 and 2002 versions) read, "Stanford, what's wrong?" and the subtitles on Netflix (1982 version) read, "Francis, what's wrong?" Additionally, when ET pulls the blanket behind the TV, on the TV screen we see Frances join her grandfather and we hear their dialogue, but in the next shot as ET stumbles out from behind the TV very drunk, even though we hear the TV's continued dialogue, what we actually see on the TV screen is a repeat of Frances joining her grandfather again, and then it jumps to the scene of Peter in the stall with Francis.
Other mistake: This concerns the 2002-Version. For this version a lot of scenes have been changed/remastered digitally, e.g. E.T.'s mimic, the flapping of Elliot's coat during the bike flight, or some cloud movement during the night scenes. Even the guns were changed into walkie talkies. But every person who was holding a walkie talkie is still pointing out his trigger finger as if holding a gun.
Other mistake: When Elliot and ET finally meet in the backyard at night, ET returns some of the candy that Elliot had left for him. In the shot before ET places the candy before Elliot, we see him standing with all his fingers extended, so he is definitely not holding any candy in his hands. He is also not wearing clothes, so he has no pockets. Where was ET keeping the candy before giving it back to Elliot?
Other mistake: When one of the bikers escaping from the cops cries "We made it!", 15 men appear from each side. Plus, there's a dozen or so police cars in front, as it is later revealed. Although this adds up for more action and suspense, it is absurd to believe neither he nor any of Elliot and Mike's friends saw none of them.