Here's an interesting way you might be able to lock a key inside a car with a fob. I know it works like this on a Prius, as I was the person tasked to bring the spare fob. Leave the fob in the car. Hit the lock button. Shut the door so the first last catches but the second does not (the door would be ajar). The Prius remained locked. Call someone to bring spare key. While waiting, push the door so it's no longer ajar. At that time, the car unlocks because they fob is inside. Call the person bringing the spare fob and tell them the fob isn't needed. Or, if as stated, the car was wet inside the car could have been locked with the fob while a window was down slightly (or the sunroof open at least partway) and the fob thrown inside after the car was locked. This would likely not unlock the car.