Open the attached mission and watch the three squads (use team switch) cross the bridges in Agia Marina. The ai will often get slightly confused on the bridge, and one or two members of each squad will most likely get stuck temporarily or permanently on each bridge.
(OLD)Go to the editor and place down some units in Agia Marina. Give them a waypoint or order them to move somewhere via squad orders during preview. In particular, put groups or single ai on one side of either bridge and order them across (or give them a waypoint). Watch as they get stuck and begin circling.