No Bottles...No Cans...No People - S4-E2
Factual error: Johnny makes two direct-dial calls from his car phone and is instantly connected - something not yet possible in 1971. His calls would have to go through a mobile operator before connecting. (00:32:30)
3,000 Crooked Miles To Honolulu - S4-E4
Factual error: The professional hitmen murder their victim in the hospital with a silenced .38 revolver. You'd think the mob would know better. Silencers have absolutely no effect on revolvers. They only work on closed-chambered, automatic weapons. (00:46:20)
The Ninety-Second War (1) - S4-E16
Factual error: An injured McGarrett is trapped in an overturned car, which emergency workers flip over before cutting him free. No rescue crew would ever do this: such violent movement could kill the patient. It's crucial that crash victims be extricated without causing further trauma: McGarrett would be freed leaving the wreck exactly where it was - upside down. (00:07:25)
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.