There's a glitch that exists with fusion - You can still interact with units as they fuse. This allows things like making a water heal while you fuse it with a fire to explode, or say, make a miner out of an earth while you fuse a blind gate. The earth you get from the blind gate is NOT the same one you fused from, it's a new earth that is spawned in after the effect of the gate wears off. What this means is that by using blind gate you could keep refusing that same earth to get free miners. It's not effective currently, however, because you do not get the air back. If you were to get the air back from a blind gate (other than the obvious tactical advantage it would give you in being able to rescue two units in a bad spot) you could fuse infinite chomplers.
Elementals is totally not a buggy race.
That's quite interesting. I myself have attempted something like the combination glitch as you described a couple if weeks ago, against the AI, but it didn't work to morph the earth when combining into a treature (probably just timed it wrong, though)