Cocoon (1) - S1-E1
Other mistake: After the funeral, McGarrett walks up to his friend. You can see not only McGarrett reflected in the man's shades, but the spotlight illuminating him following him along the wall.
Other mistake: The CSI technician dusting for fingerprints on the gun isn't wearing gloves. He proceeds to pick up the gun in his, ungloved hands and hand it to an ungloved police officer thereby adding their fingerprints to the gun. Very sloppy police work.
Other mistake: The coroner says he strangled the women with his right hand. When he goes to strangle the final victim he uses his left.
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.