This film and its predecessor Avengers: Infinity War (2018) were filmed entirely on digital 2D IMAX cameras, making them the second and third Hollywood movies after Sully (2016) to be shot entirely in digital IMAX in an exclusive open-matte aspect ratio of 1.9:1.
The first official trailer for the movie broke the record for the most views in 24 hours, reaching 289 million views across all sites the trailer is watchable on (YouTube, Twitter, Instagram, etc.) and topping Avengers: Infinity War (2018)'s trailer record of 230 million in 24 hours.
In September 2018, the Russo Brothers posted a picture on social media of the film's set, with the caption "Look Hard". This lead many to speculate and believe the title of this film was hidden somewhere inside the photo.
As Marvel will not officially own any of the film rights to the Fantastic Four and X-Men characters until 2020 after Disney purchased 20th Century Fox, none of those characters will appear in this second film, as both Infinity War films had been in production way before Fox and Disney's deal.
The title "Endgame" was not only heard from a comment from Dr. Strange in Avengers: Infinity War but it was also mentioned in Avengers: Age of Ultron. In that movie, Tony Stark says that the alien invasion from the first Avengers movie is the endgame.
The first trailer was posted by Marvel Entertainment simply as "Marvel Studios' Avengers - Official Trailer", without the film's title in the name of the video, in order to surprise the fans with the title's reveal at the end of the trailer.
The first trailer was scheduled for December 5th, 2018 but was delayed due to former US president George Herbert Walker Bush's death. The US government declared December 5th to be a nationwide day of mourning for Bush.
During an event of Guardians of the Galaxy Vol. 2 (2017) in April 2017, Zoe Saldana revealed the title of the film as Avengers: Infinity Gauntlet. Following this, James Gunn announced that was not the title.
The North American release date was moved up a week earlier from May 3rd to April 26th, 2019 after the first trailer and title released on December 7th, 2018. There was much speculation that Marvel Studios would do this, as they moved "Infinity War's" release up a week as well, in order to reduce the possibility of major plot leaks from countries that released the film earlier.
Brie Larson (Captain Marvel) and Chris Evans (Captain America/Steve Rogers) have previously starred in Scott Pilgrim vs. the World (2010) together before either of their appearances in the Marvel Cinematic Universe. Larson played the rock star Envy Adams (Scott's (Michael Cera) ex-girlfriend), and Evans played the action movie star Lucas Lee (one of Ramona's (Mary Elizabeth Winstead) Seven Evil Exes). In addition, that movie was directed and co-written by Edgar Wright, who wrote the original screenplay for Ant-Man (2015) (a character who also appears in this movie) but dropped out as director for that movie due to his creative clashes with Marvel Studios.
Release Date Change: The original release date was May 3, 2019. However, following the success of the opening of Avengers: Infinity War in the last full week of April, Marvel opted to replicate that move here.
The trivia items below may give away important plot points.
This is Robert Downey Jr.'s last contractual obligation to play Tony Stark/Iron Man for Marvel Studios. Downey has stated he plans on being involved with the Marvel Cinematic Universe longer than his current contractual commitments are structured, so many are led to believe he will sign a new deal after his current one has concluded.
Set photos leaked showing Robert Downey Jr., Chris Evans, Chris Hemsworth and Tom Hiddleston wearing outfits and costumes from the first Avengers film, as well as the rubble-filled New York set during which the final battle of The Avengers (2012) is set. This leads many to believe that either a flashback sequence or time travel will play a major role in this film. The fact that Ant-Man is seen among these characters creates the speculation that he will be the one to travel back in time by means of the Quantum Realm; this theory seems all the more likely after the mid-credits scene of Ant-Man and the Wasp (2018) where he becomes trapped in the Quantum Realm after receiving the warning to avoid the time vortex.
Clint Barton appears in Japan with the identity of Ronin in this film. This is based on the comics, where in the aftermath of the Civil War event he took up the Ronin identity during a mission to Japan.
Rumored to be titled Avengers: End Game, after a comment made by Doctor Strange in Avengers: Infinity War (2018). This was also more believed after a fan looked at one of the cinematographers' credits, where it listed the title Avengers: End Game in the films he has/or will do. This was later confirmed to be the case.
The Downer Ending to Avengers: Infinity War was originally going to be this film's Downer Beginning; had that been the case, Infinity War would have ended with Thanos completing the Infinity Gauntlet before actually using it in this movie. However, the creative teams working on the two films decided that it best suited the story to have the actual Cliffhanger follow the Badass Fingersnap itself and to show its fallout before making viewers wait a year to see how the story would be resolved.
Bruce Banner and the Hulk merge into one identity that dubs itself the Professor. This is based on the Merged Hulk (Banner and Hulk merged into one body), and is named after the Maestro (another merged form - "maestro" is Italian for "Professor"; however the Maestro was a villain in the comics, while the Professor is still heroic).