An overfilled engine can also huff enough oil into the combustion chamber(s) to hydrolock an engine.
Since the oil will not compress this means that something is likely going to give. This can range from an engine locking up suddenly and suffering little or no damage to something major like a bent or broken connnecting rod.
Higher RPMs on the highway is when this most likely would occur. A catastrophic failure certainly can occur from overfilling the oil.