In Lord of The Rings: The Two Towers (2002), one of the Elves at Helm's Deep is played by Daniel Falconer. He works for WETA workshop and actually designed the Elvish armour for the movie.

Aftersun (2022) — the opening shot showing miniDV footage of Calum features a faint reflection of Sophie, reminiscing on the videos she recorded of her childhood vacation.

The background animations in the opening credits of Scott Pilgrim vs the World (201 are related to the characters of the actors, and for the evil exes their number appears in the last frame.

In Patriots’ Day (2016), Dun Meng who fled a carjacking by the Tsarnaev brothers is played by Jimmy O’ Yang. In this scene the real Dun Meng is seen to the left.

In A Goofy Movie (1995), you can see in the diner scene that Goofy’s keychain is the Disney logo

In "The Peanuts Movie" (2015), the school paper's article about the talent show that Charlie Brown helped Sally win includes a quote from Sally claiming that she's going to Disneyland

In John Dies at the End (Don Coscarelli, 2012), time travel is a plot point. In David's house there's a DVD for Don Coscarelli's Phantasm V (2016), 4 years before its release on physical media.

In The Departed [2006], Dignam repeatedly refers to Costigan as a “Lace Curtain” Irishman. Lace Curtain Irish was a 19th & 20th century slur for a well off Irish person. (Shanty Irish was for poor).

In Shazam: Fury of the Gods (2023) this character is played by Michael Gray the original actor who used to play Billy Batson in the 70’s TV series Shazam!

John Wick - Chapter 2 (2017) The Female assassin who shots John Wick in the back is played by Heidi Moneymaker. She Stunt Performer and then wife of the movie's director Chad Stahelski

In Supercell (2023), when Will is searching for his storm-chaser dad on Google, Bill Paxton appears first. Bill Paxton also played a storm-chaser, Bill Harding, in Twister (1996).