Rifts apparently can be found less often as of a “recent” change, but since games_and_glory plays an older (stable) version (as s-/he stated somewhere else) it’s quite possible that s-/he still runs into them on a regular basis (and I’ve seen them in older versions in labs too).
Minefields are still in the game, I run into one recently (luckily not literally) while testing something else… they just changed in appearance (and frequency).