There is a possible exploit with Nydus Worms when placed against a cliff edge (Nydus Worm is on the higher ground). If an opponent plants down Force Fields to partially surround the worm, using the cliff as part of the wall, units that emerge from the worm, after filling the available space immediately around the worm, can materialise on the other side of the Force Fields, thus breaking the contain.
Reproducibility: Unknown (requires a very particular set-up)
Estimated Severity Level: 3 (behaviour is counter to what the defending player would expect)