I've only played a few times, but one thing has stuck out in my mind. Rather than having Arcade and Physics modes displayed in the chat log, I think an indicator would be better. While it is fairly easy to tell which mode you are in, this would help you remember, and not add to the chat screen.

Sounds like a relatively simple modification, could be helpful (especially when I forget to toggle back to arcade after fighting stuff and smack into an asteroid... or the rim of the docking bay). Perhaps have it toggleable, in case certain people disagree?

I think what might be useful would be a change in the engine status indicators from physics to arcade. The right-hand energy indicator would remain the same, but the left-hand thrust indicator could be what it is for Arcade, and be something different that maybe indicates direction of thrust for Physics. Most importantly, it would be a different shape so that at a glance, you'd know exactly which mode you're in, without having to make a potentially fatal experimental maneuver. For instance, I was frustrated this morning (trying to get back from 56c is pretty frustrating - especially considering how many times I had to make stupid mistakes and die to lose that much money), and I didn't notice that I'd forgotten to switch from physics to arcade mode when I was returning to the station. The resulting impact was quite spectacular, and somewhat discouraging since I now had to try to fly back into a swarm of Artemis Collectors and (type)-47 Assaults to collect free-floating cargo to try and get money in a free bus.