Quote Originally Posted by Yukimura
I loved how earlier on when he flash stepped none of the guards seemed to have any idea what it was, indicating they are either retarded or the flash step, one of the 4 basic types of Shinigaimi combat ability, is unknown to lower ranking souls in the Seiretei.
I think they didn't know what happened because Ichigo was so fast that they couldn't actually see him. And to them Ichigo was just some random shinigami so they had no reason to suspect he could perform captain level flash steps. When most people see Kuchiki Byakuya perform a flash step they're left with a "wtf just happened" moment as well and Ichigo is just as fast, if not faster, than Byakyuya.

Although I agree with Kraco, I don't see why Ichigo just didn't let a little bit of reiatsu out and incapacitate all the guards in one go.