1) The Coming Ragnarok
The biggest connection to the wider MCU to be found in Doctor Strange is, of course, the mid-credits sequence that forms a teaser for the upcoming Thor: Ragnarok and confirms that Stephen Strange will be putting in an appearance in the movies.
The scene features Thor visiting the Sanctum Sanctorum to get Strange’s help with locating his missing father, Odin (last seen having his throne poached by Loki in Thor: The Dark World). After making clear his dislike for Thor’s brother Loki, Strange (who, by the way, is wearing his usual yellow gloves from the comics in this segment) agrees to help.
The main question we have about this scene is whether it’s lifted straight from Ragnarok, or just a tie-in to it. Thankfully, Doctor Strange director Scott Derrickson has explained it:
“Taika [Waititi] shot that – I can’t say if it’s from Thor 3 or not, but we had our set up and were going to strike it after I finished shooting and it’s a very expensive set with the chamber of relics and the window and everything… I don’t know where they were on the script process, but it was before they were in production. Taika wrote that scene and came in and shot it.”