In Steven Spielberg's Duel (1971), the exterminator car that David Mann mistakes for a police patrol car is called Grebleips Pest Control. Grebleips is Spielberg spelled backward.
In Spider-Man: Homecoming, Spidey jumps over a car while chasing the Vulture goons with a license plate of ASM-267. The Amazing Spider-Man 267 comic tells the story of Spider-Man in suburbia, which served as inspiration for this chase.
In the 1982 Tron movie, in one scene as the ship crosses the light beam path there is a huge Mickey Mouse head below it on the ground.
24Spider-Man: Far From Home
In Spider-Man: Far From Home (2019) one of the movies available for Peter in flight is "The Snap" directed by Paul Greengrass. Paul Greengrass is a real-life director responsible for "United 93", "Captain Phillips", "Bloody Sunday" among a few other dramatized films based on real-world events.
25Eternal Sunshine of the Spotless Mind
In Eternal Sunshine of the Spotless Mind (2004), titles of the books aren’t visible in the bookstore scene because Joel can’t remember all of those details.
26Return of the Jedi
There is a Mon Calamari who can't find his monitor in Return of the Jedi.
In Frozen, the ice in Olaf’s drink is shaped the same as his body (head, torso, butt, feet).
28Men in Black
In Men in Black (1997), when Will Smith is looking at the two space ships at the MIB headquarters, if you look in the background Zed and K are there typing on the computer. But if you look closer you can tell that they're not even touching the keyboard.
In Harry Potter and the Sorcerer’s Stone (2001), Harry’s scar hurt not because of Snape, but because he was facing the back of Quirrell’s head aka Voldemort.
30The Hunger Games
In The Hunger Games (2012) when Katniss is hallucinating/remembering we see all the coal miners have her father's face.