So, dueling with my brother earlier tonight, I came across a new bug that I can't believe hasn't been found yet.
If the barbarian kills a unit, he can still sprint (because of his attack again ability) when sprint itself says cant be used after an attack or before one.
Unless I happen to be wrong about this rule.
More clarification:
If a barb moves and kills a unit he cannot sprint.
But if a barb kills a unit first, than moves, it allows him to sprint after the move.
Good to know, thanks dies!