Poor Benny! You could have escaped with him!!
I have yet to fix some bugs like you've seen hahaha However, Benny's movement is 'normal'... it's a glitch who try to help (it's 'not the best mount') xD
Oh, and maybe you'd like to play also the multiplayer mode if you didn't try it, just for fun :)
Thanks for playing and you know.. have a nice day :P