Continuity mistake: Aboard the boat, when Danno draws his gun, both his suit and his tie change colors and patterns completely between takes.
Continuity mistake: McGarrett wears a blue suit on the ride to the airport, but when he gets out of the car, his suit is brown.
Continuity mistake: When the police cruiser with Danno aboard leaves HPD HQ, it's a 1967 Ford Galaxy 500 with wind wings. But in the next shot of it on the Honolulu streets, the car is a '71 or '72 model with no wind wings. (00:43:30)
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.