I found 2 glitches while playing:
1. I think that the soldiers should "phase out" some of the walls (just like in Fallout 2, when you were on a "blind" spot") or, if this is not possible, visible aliens should be outlined and highlighted. Check out this picture:
My soldier is inside the UFO but although he is in direct visible line with an alien, I couldn't spot him, so I had to move the cursor around, until it turned into the targeting cursor.
There's also another alien outside the UFO and I can only spot him from his head...to be honest, I just shot him from inside...probably there was a hole somewhere! But still, if he was visible, an outline would help a lot!
2. When my soldiers exit the dropship at a terror site, only the shadow from the alien is visible. the actual sprite is missing.