Actor-Inspired Element: The scene where the Cloak of Levitation wipes away Strange's tears wasn't in the original script. On the day they were filming the scene, Cumberbatch suggested the idea to the producer, who burst out laughing and liked it so much he directed the special effects crew to make it happen.
Awesome, Dear Boy: Mads Mikkelsen and director Scott Derrickson went on record that one of the reasons that the former signed up for the film was that "he got to do kung fu".
California Doubling: Averted for the the segments taking place on Nepal, which are really shot there, but played straight for some of the scenes in New York City, which were shot in London, England. Naturally averted with the brief moment taking place in London.
Celebrity Voice Actor: In the Mexican Spanish dub, Doctor Strange is voiced by famous singer and actor Beto Castillo.
The Danza: Coincidentally. The character was named Wong long before Benedict Wong was cast.
Scenes containing Donna, Stephen Strange's sister, were deleted.
Stephen Strange heals a dog's broken leg in Kathmandu.
During the first ritual to draw power from the Dark Dimension, one of the Zealots fails, proving his faith not to be as strong as the others', and Kaecilius executes him.
In the church the Zealots will use as their headquarters, Kaecilius confronts the priest: after questioning the meaning of an "afterlife", he offers evidence that such a thing doesn't exist, and kills the priest.
Suddenly finding himself in the New York Sanctum, Doctor Strange briefly confronts Master Daniel Drumm before he goes to face the Zealots.
Dueling Movies: Released the exact same day as another film with a lead character who is unwilling to kill people and is put in a situation that confronts that directly, Hacksaw Ridge from Mel Gibson (who was just starting to recover from his decade-long Persona Non Grata stance in main Hollywood). That movie has three names who were once attached to Marvel and Disney (Andrew Garfield, who played the second cinematic Spider-Man, Hugo Weaving, who played Red Skull in Captain America: The First Avenger, and Bill Mechanic, who was the boss of Walt Disney Home Video from 1984 to 1993/1994. Gibson also voiced John Smith in Pocahontas). Strange wins, but Hacksaw Ridge also had to deal with Mechanic's former supervisor Jeffrey Katzenberg's DreamWorks Animation, who released Trolls alongside the dueling movies (it's one of the last DWA films to involve Katzenberg after he sold the studio).
Dyeing for Your Art: Benedict Cumberbatch hit the gym and went on a strict diet to suitably bulk up for the role.
Executive Meddling: Zigzagged. In one interview, Writer C. Robert Cargill confirmed that the decision to change Strange's origin story from taking place in Tibet to Nepal and the Race Lift of the Ancient One was done to avoid the film being Banned in China, since Chinese censors are notoriously touchy about Tibet and because China is very key part of the overseas market for Hollywood films. However, he later tweeted that there being political pressure from China was speculation on his part, followed by Kevin Feige responding too that the Ancient One's casting was not affected by political reasons. Cargill defended the decision, noting that there was no "good" option regarding the casting of the Ancient One, claiming that if they had gone with an Asian actor or actress, then the character would have been seen as a racist stereotype.
Fake Nationality: Master Hamir is presumably Chinese, just like in the comics. His actor is Indonesian.
I Knew It!: A lot of folk had already deduced that the Eye of Agamotto is an Infinity Stone, and more specifically the Time stone, since the first good look at it, based on such things as its color, comments by Feige on its abilities, and the fact that with the Infinity War film fast approaching, the then-unknown stones would need to be introduced somewhere.
Jossed: In the film, it's mentioned that Strange turned down the opportunity to fix someone's spine after they'd been badly hurt inside of a mech suit. It later clarified that this was not intended to be a reference to the poor Hammer Industries test pilot in Iron Man 2 who gets fit with a faulty set of armor, nor a reference to Captain America: Civil War with Rhodey (as most had speculated).
Fans had fun guessing the other "secret identities" of the Infinity Gems, since prior to this film the Stones of the MCU seem to be slowly building a Fun with Acronyms with Thanos' name (Tesseract, Aether, Orb, Scepter). The revelation that the Eye of Agamotto is the fifth Stone quite obviously nixed that idea unless you count it as Necklace.
In the trailer, Strange walks backwards into the Mirror Dimension; in the film, he follows the Ancient One inside the proper way.
The line "how did you become a doctor" is changed to "How did you get to reattach severed nerves and put a human spine together bone by bone".
Kaecilius' line "I am death and pain" is absent from the movie altogether, as is Ancient One's "I've spent years peering through time, looking for you."
Wong's "Be careful which path you travel down, Strange. Stronger men than you have lost their way" line from the 2nd trailer is not in the film.
Playing with Character Type: Tilda Swinton often plays eerie androgynous characters who are usually evil, or turn out to be. The Ancient One appears benevolent but soon the question is raised as to whether or not she can be trusted. It turns out she can and she's only Good Is Not Nice at worst.
Schedule Slip: The film was going to be part of Phase 2, but when Benedict Cumberbatch's schedule wouldn't allow for it, the crew wanted him for the role so much that they delayed production until he could do it.
Short Run in Peru: The movie was released in many countries a week before its US release.
Benedict Cumberbatch and Chiwetel Ejiofor had previously worked alongside each other in 12 Years a Slave.
The year before this, Chiwetel Ejiofor and Benedict Wong appeared together in The Martian.
Amy Landecker was cast to play a very small part in one of the opening scenes opposite Michael Stuhlbarg because director Scott Derrickson was a fan of them together in A Serious Man.
Throw It In!: Rachel McAdams's startled reaction in the broom closet was genuine, since the mop handle fell completely by accident, and scared McAdams almost out of her skin. Scott Derrickson decided to keep the reaction in the film, since she never broke character.
Neil Gaiman and Guillermo del Toro pitched a Doctor Strange movie back in 2007, but Marvel passed on the project because Doctor Strange was considered a low-priority character at the time.
Benedict Cumberbatch originally wasn't sure if he would be able to star in the film, due to commitments to a production of Hamlet - as the film's original release was set for July 2016. When it was pushed back to November, he was able to come on board.
Wong was originally not going to appear at all, as Scott Derrickson was uncomfortable with the racist stereotypes surrounding the character. However, he changed his mind after the decision was made to Race Lift the Ancient One, as he was now worried about the fact that there were no Asian characters in a movie that takes place largely in Asia.
Originally the film was to feature a prologue set in CERN (Conseil Européen pour la Recherche Nucléaire, aka the European Organization for Nuclear Research) and would feature a discussion on parallel dimensions. The filmmakers felt this was too scientific for a magic-based story, and removed it.
Derrickson wanted Nightmare to be the main villain, but Kevin Feige argued that introducing the Dream Dimension would require too much additional Exposition in a film that was already full of it.
As this film starting shooting at roughly the same time that the MCU was restructured (the script had also been long finished), this is the last film in the franchise to be produced under the old structure of Marvel Studios being a division of Marvel itself. Every movie since has been developed as a separate division of Disney propers live action umbrella with no input from the executives at Marvel. note Prior to August 2015, Kevin Feiges boss was (now retired) Marvel CEO Isaac Perlmutter. Perlmutter was infamous for being cheap and overriding Feiges creative decisions. The tension finally came to a head on the set of Captain America: Civil War when Perlmutter tried to cut Robert Downey Jr. out at the last second because of his salary. Feige went to Alan Horn, the head of Disneys live action group, and threatened to quit if he didnt get out from Perlmutter. Horn gave Feige what he wanted and now Marvel Studios is a division of Disney rather than of Marvel. Horn is now Feiges boss instead of Perlmutter.