Here Derrickson confirms that this wasn’t an accident, but actually an intentional reference to the Bill Murray movie Groundhog Day, in which a television weatherman is forced to relive the same day over and over again.
Fans have joked since the film came out about the similarity, but it appears Scott Derrickson made the joke first.
The tweet that Scott Derrickson references shows a screenshot of a brief image that we see in the film of Stephen Strange’s watch, which confirms that the date is February second.
Doctor Strange ends with the new sorcerer using the Time Stone to put himself and the entity Dormammu into a perpetual time loop that repeats the same few moments, including Strange’s own death, over and over again.