And it was in park (automatic of course) and was shoved a foot or so back. Can this damage the tranny?
Yes it could plus a lot of other things, depending on how fast the other car was going. On the tranny, have them put it park and try to push the car by hand. If it does not move the parking pin is probably OK, if it does move the pin is sheared. Just to verify try to push it in netural to make sure you can move it. Have someone in the drivers seat to hit the brakes in case the car gets going too fast .
The frame/unibody could be damaged, the suspension could be damaged. Best to get their insurance company involved and get the car to a mechanic for an inspection.
@johnbarry, if the owner hasn’t called his auto insurer yet, he should do so immediately. This is why we in sure our cars. The insurer should take care of fixing it.
Is this a Front Wheel Drive; Rear Wheel Drive; or full time 4 wheel drive?
If the transmission survived the impact, check the engine and transmission mounts as the torque applied to the transmission has to be resisted by the mounts unless the engine and transmission fall out of the vehicle.
Was the parking brake on? That might make a difference here.
It is a 2006 Nissan Maxima. Your answers are pretty much what I thought although the answer from SteveCBT is something I did not think of. my neighbor had it parked in front of his house when it was struck by a hit and run driver at 10:30 at night. Thanks to all who answered my question.