It can be a hell of job fighting bad guys on GothamAnd if you’re a crime crusader like Detective James Gordon, you have to watch for pillars as well as swinging fists…because pillars always like to hit heads. Actor Ben McKenzie who plays Gordon clunked his noggin against such pillar during a fisticuffs scene on Friday.  McKenzie, who celebrated his birthday yesterday, Ben McKenzie injured on set of 'Gotham'posted some photos of his gash on Instagram saying, “Holy concrete wall, Batman!” and “Happy Birthday to me. Fight sequence gone awry. Don’t ram your head into concrete pillars kids.”  All bandaged up, McKenzie gave props to his medic, exclaiming, “Doc Sherman at New York-Presbyterian, you are a career saver. Thanks for stitching me up nice. Back to work Monday.”  Gotham airs Sept. 22 at 8 p.m. on Fox and follows the Batman lore during the winged crusader’s childhood days after he loses his parents. WBTV and Fox have a big premiere of the show planned for this Monday at the New York Public Library. McKenzie is expected to attend.