Freespace 2 can way exceed 300 m/s as far as I know.
There was one for Age of Empires I - I don't know how it happens, but sometimes you attack a cavalry (or hero) and run away (with another cavalry or hero) and the AI one stands there and attacks nothing with its sword. It keeps doing this until it gets attacked again or the computer runs out of army or you build a wonder. You can also get balista towers to make the shooting noise but nothing comes out when you attack it with a horse archer at max. range and run away.
Another one for FS2 - place heaps of capital ships in each other, like cruisers, and watch them fly apart when you start the mission. Also watch the AI sometimes fly into capital ships because they are trying to get you when you are right next to it, or they are trying to escape you.
Return to base right next to a large ship that is about to blow up, and watch your fighter get blasted away from its warp. You don't die since you are invunerable as soon as the camera changes to "subspace drive" view.
As for Elasto Mania - having any wheel between two almost straight polygons and pressing the brakes will blast the wheel towards the wider end. Of course if you sretch too far then you get internal error. Change direction when spinning fast or stretched (use elmaNITRO) and grab a screen shot when your bike disappears or the suspension "detaches" from the wheels and goes anywhere.
FS2 warp in two large capital ship right in front of each other and watch the larger one push the other back into its warp! But then it magically appears at point blank range in front of the other one after its warp time ends.