Cast the Expert: The doctors are real doctors. Spielberg mentioned that this was necessary as they would be better at rapidly spitting out terminology that required years of medical school to learn than any actor who'd been simply given a briefing on it. Humorously, this led to some competition amongst local doctors who all wanted to be in the movie.
Colbert Bump: Sales of Reese's Pieces candy skyrocketed after their inclusion in the film.
Cross-Dressing Voices: Played straight with E.T. in the original version and in the Japanese dub, but averted in the Mexican Spanish dub, where he is voiced by Héctor Lee.
Harrison Ford filmed a scene as the principal of Elliot's school, set after he frees the frogs, which Spielberg cut because he felt Ford's presence was too distracting.
Two deleted scenes were reinstated for the 20th Anniversary Edition: Elliot shows E.T. the bathroom and gets a call from his mother and fakes throwing up on the phone. E.T. plays around in the bathtub and Elliot thinks he's drowning, but it turns out he's rather enjoying himself. The other one shows Mary tracking down Mike and Gertie during their trick or treating. Gertie (now in her cowgirl costume) spills the beans on where Elliot is, and Mary (smiling, but insistent) tells them to get into the car.
There was a subplot cut in which E.T. was in love with Elliot's mom. He goes into her room and leaves a Reese's Pieces on her pillow.
There's a scene of when E.T.'s getting Elliot drunk. Elliot gets sent to the nurse's office and writes the plans for the communicator on the wall.
There was originally an alternate ending showing the boys playingDungeons & Dragons with Elliot as the dungeon master. The camera pans up to the roof, where the communicator is calling out to E.T.
Do Not Do This Cool Thing: Since the way the government agents menace Elliot and his family in this movie casts the federal government of the USA in a rather less-than-flattering light, this movie generally passed muster with censors in the Soviet bloc and was approved for importation. Common reactions among the audiences in these Communist countries that actually got to see it, however, tended to be "So... it's Not So Different from how our government treats us here, then?" and "Wow, that's a nice house and car they've got there; are all those capitalist Americans so rich that even a divorced mother of three can afford such luxuries?"
Dueling Movies: With John Carpenter's darker take on an alien counter in The Thing (1982). E.T. trounced it with critics at the time and at the box office. But both are held up as sci-fi classics now.
Enforced Method Acting: Filmed in chronological order so that the cast could become genuinely attached to the E.T. character. Young Drew Barrymore, in particular, took it the hardest: she was genuinely frightened when she walked in on Eliot with E.T. in his room and in tears during his Disney Death scene.
Gertie's line "I don't like his feet!" was ad-libbed, as was her "Gimme a break!" response to Elliot's claim that grown-ups can't see E.T. (You can also hear her prattling away unscripted in the background while Elliot and Michael are showing E.T. maps and trying to get him to tell them where home is for him.)
Averted nicely unlike a lot of 80s movies. You can tell it was filmed in the 1980s due to the cars, the TV, and the family owning an Atari 2600, but it doesn't stick out like other examples. Many of the pop culture references they make like Star Wars or The Twilight Zone are still known by today's audiences.
On the other hand, jock older brother Michael's introduction has him playing Dungeons & Dragons without hinting at him having any geeky or creative Hidden Depths, which firmly grounds the film in the early 80s (the height of D&D's popularity as a fad) for fans of the film who are role-players.
The first choice to play Gertie? Juliette Lewis. Her father made her turn down the role and Barrymore was cast instead.
Shelley Long was approached to play Elliot's mother. She turned it down as she was already signed on for the comedy Night Shift.
Stan Winston turned down the opportunity to work on E.T.. He would regret doing so.
The book "E.T. from Concept to Classic" features many plot points and scenes cut from the script. One subplot from an early draft was to have a rival to Elliott named Lance who wanted to expose E.T. The spaceship was going to land in a parking lot, but it was changed to a forest because that seemed more magical, among many others.
The film's screenwriter Melissa Mathison wrote a script for a sequel called E.T. II: Nocturnal Fears where an evil group of E.T.'s people would come to Earth looking for him and torture Elliott and his family for information; but (mercifully, some would say) it never left the drawing board.
Corey Feldman was originally up for a role as a rival to Elliott, a dork named Lance who threatened to expose E.T. The character is in the book adaptation, but was cut from the script. Steven Spielberg promised him a role in a future film, and he would go on to be in Gremlins.
Originally E.T. was going to develop a crush on Elliott's mother. Some scenes of this were filmed before this subplot was scrapped. This also made it into the novelization.
Elliot was originally going to lure E.T. into his house using M&M's, but this proposal of Product Placement was rejected by the company's executive, who perceived the movie as having an Audience-Alienating Premise. Instead, Reese's Pieces were used, and Hershey's sold so many Reese's Pieces that they were able to become a major competitor to the Mars Candy Company. M&M's are still used in the novelization.
Steven Spielberg stated that E.T.'s species is more similar to plants than any other kind of creature and has No Biological Sex. Also, a series of trading cards from the 1980s list the family's last name as Taylor.
Approval of God: Surprisingly, Steven Spielberg not only signed off on the games concept, he actually liked the final game.
Christmas Rushed: An infamous example. "Hey Scott, make something awesome! You've got six weeks."
Creator Killer: This game is often credited for the Great Crash of 1983, which annihilated Atari and Warner Bros.'s value. While it didn't singlehandedly cause the Crash, it didn't exactly help matters, either. Atari boss Ray Kassar, who had already driven away several programmers that then founded Activision and demanded the game's short development timetable, was ousted from his position and he has not been affiliated with the entertainment world at all since 1983. Shortly afterward, Warner sold off Atari, and the classic developer completely lost all of its dominance when Nintendo, who broke off their attempted relationship and became a brand-new Arch-Enemy, released the NES and ended the crash in 1985, but they were able to hang around for another decade until Atari's inability to recover from the crash culminated in the Atari Jaguar, which finished off the studio.
Franchise Killer: In addition to being one of the ultimate Genre Killers in entertainment as far as video games go, this game also severely affected the status of Spielberg's classic film, and the E.T video game is rumored to be the reason why it took MCA/Universal another 6 years before they released E.T. on home video (it got a later reissue in theaters instead, and then it got pulled entirely for a couple of years after that run ended). This game didn't quite kill off other E.T games in utero, but guaranteed those games would be small projects, and none have been produced since 2002.
Genre-Killer: E.T is the mascot of the Great Crash of 1983, which not only reduced Atari to a shadow of its former self for the remainder of the 80s and 90s, but destroyed almost everyone else in the industry, and likely would have sent gaming into a permanent small niche or worse had Nintendo not stepped up. It's also part of the reason some other Hollywood studios, most notably Disney, hesitated in the gaming market and fumbled several times.
Likewise, the company's aggressive sales tactics, practically forcing retailers to preorder vast stocks of the cartridges, led to the famous embarrassment of having to secretly bury all the many many returned cartridges in a secured landfill, a rumor that would not be confirmed until 2014 when the evidence was (literally) unearthed.
Killer App: Inverted. The poor reception of this game, along with others, served to turn people away from the Atari 2600 as well as all other video game consoles for a few years.
Magnum Opus Dissonance: Inverted. As seen from the quote on the main page, Howard Scott Warshaw considers it an honor that this is the worst-received game on the system, as in comparison to his best work, Yars' Revenge, he has "the greatest range of anyone ever on the machine."
What Could Have Been: A game for the Atari 5200, which was said to be more generic but much more playable than the 2600 game, was in development and practically finished, but ultimately pulled due to the terrible reception of the 2600 game, and the 5200 itself not selling particularly well.