Community creator Dan Harmon was recruited by Marvel Studios to do some re-writes on Dr. Strange after principal photography. 

Entertainment Weekly reports that Harmon was hired to work on new pages following the wrapping of principal photography in New York last April.

According to the film's director, Scott Derrickson, re-shoots were needed to "to clarify logic in scenes.”

“I don’t think there are any wholesale reshot scenes,” he continued. “It’s mostly little shots within scenes to clarify points. There were some points that the audiences found overstated, and we trimmed those back in editorial, and there were some points of explanation that were not clear enough, so we’re adding a bit of clarity to those.”

Re-shoots are pretty common for Marvel movies and blockbusters in general these days so this news wouldn't be any cause for concern. Given Harmon's sitcom background, one would imagine he was brought in to punch some humour into the new scenes though it's entirely possible he's looking to move in a new direction in his writing career and the re-writes could be his audition for future work with Marvel. 

Dr. Strange is in cinemas October 28th.