97 Auto Transmission

After diong a high speed, 400 mile run I noticed that the under carrige on the drivers side, wet with transmission fluid. Upon checking the dipstick the system was overfilled. Is there a overflow/vent or valve for an auto transmission? There is no static leak so thats why I think it might have vent off instead. Any ideas. BTW i few drops of this fluid made its way to the AC,how did that happened??? Thanks