You bring up a good point. Just about all jurisdictions make illegal any device which would shoot somebody without human control.
If it ever shoots at a fireman or police officer, expect to go to jail for a long time.
IIRC, compressed air weapons were used int he First World War or the Crimean War. They can be deadly, and the one featured here can be blinding don’tchaknow. [’You’ll shoot yer eye out, kid.’]