I'd still take you to court. You'd have to still prove reasons for firing. If you have nothing to back it up, no writeups, no reprimands, nothing on record, then you cannot fire anyone without backlash.
Not only can you be held accountable for all sorts of future payment. You can be held on grounds of unfair work practices, REGARDLESS, of at-will work. Which then means, I can sue for wrongful termination, discrimination, and other sorts of nasty. I'd have your future profits for years to come, AT LEAST, IF NOT; shut your business down for good.
So go ahead and fire people for no reason. You're just lucky you haven't been bent over yet.