Why is it that shields stop the droid army's weapons but the droids themselves can pass through the shields without any problems? Would they have been able to attack the Gungans if they had something other than energy weapons, maybe something physical such as bullets or cannon balls?
Basically, the shields they used would only block things with at least a certain threshold of energy or speed.
From the Wookiepedia entry on shields:
The Gungan shields used during the Battle of Naboo blocked lasers, but droids could pass through because of their relatively slow movement in comparison to the laser bolts.
Old question, but I came across a source that discussed this. From the Episode I novelization:
The Gungan shield wall was designed to deflect large, slow-moving objects of density and mass such as artillery vehicles and small, fast-moving objects generating extreme heat such as projectiles from weapons fire. But it would not deflect small, slow-moving droids.