I found this bug where arrows shot using a bow will end right from your aim, about 2 block pixels. It always happens (on mac at least)
MC-9518
Shooting an arrow using a bow makes it land right from your aim
Resolved
Duplicate
0
DicoTheRedstoner
(Unassigned)
Unconfirmed
Minecraft 1.4.6, Minecraft 1.4.7
Retrieved
Duplicate of MC-4170, please use the search function to see if your bug has already been submitted. Currently over 51% of tickets are being closed as duplicate.