Either it's an unplayable lie and it got moved with no penalty. The spot that i can think of is the par 5 on RSG. The bridge. if ball stops on the bridge the ball is moved with no penalty.
there are a few other spots.
OR
the ball didn't actually get wet. Like on merion it finishes in the dirt near the creek. on the short par 4. what hole is that? 11? i forget.
OR
you didn't count right.
Hole 6 on congressional is an example. can still make par if hit it into the water on the second shot birdie if you hole it. same thing with St andy 1 if hit drive into the water. there are others. but those are the most common pars after water balls.