Deliberate mistake: Throughout series: Five-O was said to be Hawaii's state police force, and was shown headquartered in the Iolani Palace. For decades, tourists were disappointed to learn that in reality, Hawaii had no state police, and that the palace was a state museum, not a state police station.
A Bullet for McGarrett - S2-E6
Deliberate mistake: Han is shot several times as he dives from the board into the pool. But when his body is shown slowly floating back to the surface, there's not a trace of blood on him or in the water. (00:03:30)
Deliberate mistake: 8-4 "Target? The Lady": During the car chase, a crowd of real-life tourists is standing on the sidewalk, very obviously ogling the film crew as they shoot the scene. The footage was left in to avoid an expensive retake of the stunt chase.
Deliberate mistake: 9-12 "The Bells Toll at Noon": When McGarrett picks up Danny and drives away in his Mercury Grand Marquis, the rear view mirror is missing, probably removed to prevent it from blocking the actors' faces. It reappears later on. (00:33:00)
Answer: He was fired. He never really appreciated his character. He felt Kono was portrayed as a big dumb Hawaiian and that the stereotype was racist. He also felt underutilized. He was fired after a heated argument with the show's publicist regarding his character. It seems there's not much details given regarding the incident or the firing, so it's seems possible he upset the show's producers as well.
Bishop73
No he said something derogatory about one of the Jewish producers that's why he was fired.