So I ordered a few construction aircraft to help build a naval plant, and some of them decided now was a good time to start a space program. I've seen posts about units going into orbit, but I'm not sure if this is the same bug, these ones could be ordered around and once I did they came back down and landed. pic:
I had this exact same problem, except it was with a heavy tank, which was especially hilarious because of its slow movement speed, it slowly crept off into space. It took about 20 minutes to actually get too far out into space to see anymore, so as I attacked my allies I periodically checked on my wayward piece of artillery rolling away.