1.- This tile right here is unwalkable if you click on it, or use arrow keys to walk into it, however, you can dash trhough it. (I'm using the Retro Outfits + New Graphics client)
2.- You can hide paralyze runes by dropping stuff on them.
3.- You can't infect humans who are inside another player. People exploit this with antipush so you never infect them.
IMO, these issues can change the outcome of a match greatly, hope they get fixed soon