In Doctor Strange (2016), the titular character Doctor Stephen Strange gets in a car accident which disables him. However, this happens when he hits another car. We see that Strange's car is sent flying down and into a body of water, presumably a lake but possibly the Atlantic Ocean. However, what happened to the other car?
I'm not aware of any explicit mention of the other car, either within the movie itself, or anywhere else.
Just based on the visuals though, it looks as if -- while driving in the opposite lane to overtake a car, and taking his eyes off the road to glance at medical scans -- Strange positioned his own car in such a way that it was on the receiving end of an unintentional PIT maneuver from the vehicle he was trying to overtake.
The PIT maneuver generally only causes the car in front to spin out of control, not both vehicles, and that looked to be the case in the film. It is hard to see clearly -- given how brief the shots of the accident are, and the darkness of the nighttime setting -- but I only see one car spinning out of control, not two.
Also, if anyone else had died or been seriously injured as a result of Strange's careless driving, it seems unlikely that the film would've glossed over that, as if it wasn't noteworthy. As arrogant and self-centred as he was at that point in the story, I don't think he'd have been solely concerned with his own injuries if he'd hurt one or more other persons as well.
Incidentally, according to an article on filming locations for the movie, the collision occurred on a stretch of New York State Route 97 called the Hawk's Nest, and Strange's car span off the road into the Delaware River.
Strange leaves the city via the George Washington Bridge over the Hudson River and is soon careering along a stretch of Route 97 called The Hawk’s Nest running alongside the Delaware River, a few miles north of Port Jervis, New York on the Pennsylvania border. The dramatic name is derived from the birds of prey that nest in the area.
He’s not only exceeding the 25mph cautionary speed limit for Hawk’s Nest but is distracted by his mobile devices. Don’t!
A moment’s lapse of concentration sees him veering off the road, plunging down toward the Delaware River and the accident which is to change his life.
In an establishing shot shortly before the accident (shown below), you can see that the road was running alongside a river, rather than the Atlantic Ocean.
And if you check the video above around the 1:03 mark, you can see the lights on a bridge spanning the river, in a shot just after Strange's car has come to rest in the water.