Murder is a Taxing Affair - S6-E6
Revealing mistake: A bad matte superimposed over Cavel's rearview mirror makes McGarrett and Danno, who are actually in a car behind him, appear to be sitting in his back seat instead.
Revealing mistake: Listie was supposed to be dead, but you can see his eyeballs moving under the lids.
Revealing mistake: The teaser contains footage of a stunt-gone-wrong. The getaway truck smashes into a mock-up police cruiser that has been secured with a chain to pull it back out of the shot. The chain breaks, and is visible trailing from the bumper as the fake cruiser starts an unplanned roll down the hill. (It went on to collide with and damage two real HPD patrol cars rented for the production).
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.