Doctor Strange: 31 Easter Eggs & References You Must See

As revealed before release, there was initially going to be an Easter Egg specifically pointing to Marvel character The Black Knight. His sword, The Ebony Blade - basically Marvel's version of Excalibur - was to be included but was removed according to Barry Gibbs, the propmaster:

“It was [going to be in the movie]. That was going to go into a book called the Lexicon of Relics, but the Ebony Blade was taken out of the script. I don’t quite know why. Again, as things evolved, it wasn’t pertinent to the script. Things just moved on.”

That book didn't appear, but the New York Sanctum did include lots of artefacts, and in the background there's definitely a helmet that looks suspiciously like an uncoloured version of Black Knight's headwear. So maybe he wasn't entirely cut?