Good job on the bugfix!
Playing more than one memory of hawk still causes problems, though, just not a crash. The speed keeps stacking and it quickly becomes impossible to play except in slowmo. The speed buff also seems to be affecting the enemies, at least to some extent. Its hard to tell because of the massive lag when traveling at such speeds. I would recommend changing the increases after the first one to asymptotically approach some value, or letting players discard the card or otherwise get it out of the hand without having to gain its effect