The throttle is the most likely spot to have a problem. Cover with a plastic grocery bag, blow out the water, should recover fine.
That type of battery mount is prone to having water run downhil, as it usually does, directly into the electrical contacts, which if enough water shorts this connection, can blow the BMS in the battery and/or blow the controller, requiring some repair and replacement. Dielectric grease or silicone sealant can help, but battery is no longer easily removable, without breaking the seal.
Hub motors themselves are almost immune to electrical shorts from water, however the corrosion from long-term exposure is a problem, also the dirt and crap the water carries in can cause problems.