i wouldnt worry about the bar... i'd be more concerned about the impact your diff took. it appears to be just cosmetic on the diff though, on the outside diff cover. if the diff seems to be operating normally, then consider yourself lucky!
i'm willing to bet the diff is fine. do a few hard accel and hard braking tests... and make sure the car tracks straight and true in both conditions. make sure no noises, funny smells, weird sounds, etc... if everything feels right, then you're probably good to. based on that picture, it appears the diff just took a minor scuff and the diff cover is fully intact, lucky!
2011 E90 M3
2004 996 GT3