There's an issue with Open Zeta in that the bottom right slot has trees surrounding the gate in zone and the top left slot doesn't. this allows the top player to place factory next to mex, or further away.. etc.
Also, on that map, the trees around the bottom right spot are actually invisible for the first few seconds of the game, making it look like there is clear terrain, and when you try and place a factory your acu walks because there are trees.