Bombs seem to be checked serverside so that they cannot be hacked (assuming for farming purposes), but arrows aren't. They should be.
I noticed around last summer that many people on the daily kills boards mysteriously drop 0 arrows every time you kill them, but respawn shooting a million more of them. I was PKing in Graal City last night and noticed two people who were doing this while PKing in these massive mobs. It's way too easy to hack infinite arrows using CheatEngine, and seeing as how many people have been speeding recently I assume it's probably already a problem that just no one else has really took notice of.