During production of his film Sinister (the film that most likely got Derrickson the part to direct Doctor Strange), he worked with writer C. Robert Cargill, his co-writer. They also spent a period of time developing a script for a Deus Ex: Human Revolution adaptation (which presumably is still in development purgatory). Most notably of this, however, is that Derrickson had Cargill on set every day for the course of filming, to get input on how the script was being translated to the screen. They also co-wrote the sequel, but Derrickson didn't direct that film
Just recently, the same writer announced on Twitter he had suddenly and suspiciously moved to London, right when Doctor Strange is about to start principal photography.
Then, that very night, he went to see the film's star, Benedict Cumberbatch perform Hamlet on stage:
A temporary stay in London for someone who's worked closely with Derrickson in the past, seeing the performance of the film's main star for a period of time that wouldn't be out of place to match the principle photography of a feature film...if it is a coincidence, it would be an awful lot of coincidences happening at the exact same time. So what do you think? Is C. Robert Cargill really helping write the film or is it just a wacky happenstance of life?