After heavy rain, car was acting weird .

Hello,
It was all night heavy rain. In the morning I start the car and some weird things happening. In the dashboard showed up some lights included check engine light. Engine sounded OK but when I shut off the car, dashboard lights stayed on, headlights stayed on and the only way to shut it off was disconnect the battery.
Next morning when car dried, I start the car and everything seems OK. Only mirrors didn't close when I lock the car. The mirrors closed after I pressed the button on door.
I called to my mechanic and he said something is getting wet. He pointed some locations, seems like fuses locations, but the question is, if is it common in these cars and what most likely getting wet.
Thank you