Running shots in reverse has a range of legitimate uses, whether it's for comedic effect, artistic storytelling purposes, or ensuring that your student film achieves maximum pretension. When it's effective you don't even notice, but as soon as you do pick up on it, it's like the movie's been thrown into a weird alternate reality where up is down and Internet comments are nice. Take the closing scene of Carrie, where the sole survivor of prom night walks to Carrie's grave. In reality, she walked backwards and then they ran the footage in reverse to create the surreal, dreamlike atmosphere, but if you keep an eye on the red car going backwards in the background, it just ends up looking goofy.
"Christ, I don't want to hear the damn prom story again."
"Just reverse dude; I don't think she saw us."
For a more obvious example, check out the waterclimb, the rare opposite of a waterfall, in this clip from Anaconda.
Columbia PicturesPlease stick to the shots and effects that you're used to.
While the shot is of the boat backing up, presumably it was easier to film the boat moving in and then run it in reverse, with the logic that viewers would all be too busy drinking, getting high, or making out to notice the water's casual defiance of gravity. Uma Thurman taking a needle of adrenaline to the heart in Pulp Fiction was run backwards too, presumably because not even Quentin Tarantino wanted to see one of his actresses stabbed in the chest.