It's dumped fuel, the stream is mostly water vapor from the peroxide tank. With the amount still issuing from the wrecked one, it should be a big hole in the ground!
No, that's my undercarriage while it's fully deployed, I simply landed in the wrong part of the grass field (there is an assigned strip) going too fast, but slowed down enough to not die during the flip...
Also, that stream still emanates when you're out of fuel...