Chicago Med

Dr. Will Halstead was introduced before the backdoor pilot as the brother of 'Chicago P.D.''s Jay Halstead.

Colin Donnell's character's mother is dead, as was in 'Arrow', where he starred previously. His character also has issues with his dad in both shows.

Dr. Natalie Manning's name was originally Lilly before the show aired, as clearly seen on her lab coat in early promotional pictures, but was changed before the pilot episode.