In the fight scene when Cull Obsidian and Ebony Maw arrive in New York City to take down Tony Stark, Wong, and Doctor Strange, Cull Obsidian is seen with a material hanging from his belt that looks a lot like Captain Marvel’s suit leading to speculation that Cull and Captain Marvel had met and fought before. I guess we’ll need to wait till Captain Marvel premieres in 2019 to find out.
