- Safe areas around towns extend upwards all the way to the ceiling of the current floor. If somebody were to fall from up there into a town, he'd be perfectly fine (Heathcliff pointed that out during the "inner area murder incident")
- Nobody used heal/teleport crystals in the battle against the first boss (Ilfang the kobold lord) because they were almost impossible to obtain on the first floor.
- While the visuals were realistic and all and taste was reproduced (although it needed quite some effort to reproduce "normal" food from the real world)Also, facial expressions didnt have the subtle "something" they would have in the real world.Certain sensations, especially being in water were not possible to be precisely replicated by the Nervegear. So taking a bath in the virtual world would feel differently from taking a bath in the real world
- You don't know the name of someone in SAO unless he tells you or you challenge him to a duel. Once you know his name, his name will always be displayed next to him
- There are measures against sexual harassment in SAO: if somebody grabbed a player too hard (or in inappropriate areas) the victim would get a message window. If he clicked "ok", the offender would be automatically teleported into a prision area on the first floor. This also applies outside of safe zones
- While in a safe area, it is impossible to move another player against his will unless he is asleep and a stretcher is used (PK was done that way. Sleeping player was loaded on the stretcher and carried outside a safe zone and then killed)
This works both ways, a large group of people can pervent other people from moving around just by standing there (The "army" often used that tactic on the first floor to extort "taxes".
Outside a safe area, this rule does not apply.
- Bow & arrow weapons existed in Aincrad, but they were so hard to use (or rather, it was very hard to hit something) so nobody bothered using them.
- It was impossible to break into someone else's room no matter what if the door was locked and you had not permission to enter.
- The "cardinal system" managing SAO also handled gameplay balancing, bugfixing and removing exploits.
If somebody found a good "farming spot", the spawn rate would immediately be adjusted. Same applies to any errors and balance issues.
- SAO is in the same universe as Accel world, but its events happened a few decades before Accel world (Accel world and SAO were written by the same author, remember?)
He even made a crossover chapter in a side story where we get Kirito vs. Silver crow
If you watched/read the LN of Accel world, you should be familiar with the "Incarnate system" (the ability to overwrite the rules or defy some of these rules)