+1 for enemies you're not supposed to be able to defeat, at least when first encountered. This shouldn't be limited to the city of BG (guards calling for help from powerful people in the city, important shopkeeps being high level or having high level guards/defenses), but also in the open world (stumble upon a level 10+ enemy in Act 1).
Obviously the game shouldn't initiate lethal combat with these entities; the player should have to (stupidly) choose to do so. And these enemies should be higher level, not just invulnerable to damage or untargetable. It is possible to defeat them, likely through exploits/cheese, but so unlikely as to be heavily discouraged for all but challenge runs.
I'd also like it if, in cities, stealing was responded to by calling the guards to bring you to jail instead of the victim (and every single nearby NPC) becoming hostile. The guards would ask you to surrender, but if you chose to fight they'd deal non-lethal damage to you and then take you to jail. There you could either pay the fine or escape, but if you escaped then as previous posters suggested no one would want to trade with you. On the other hand, if you initially beat the guards, hopefully the game would also consider whether you murdered or just knocked them out. If the former, the city becomes hostile. If the latter, most traders will still trade with you, but traveling through the city would risk encountering stronger guards sent after to to take you to jail. And repeat until resolved.
