Magnum PI epsiode that needed McGarrett

I recently watched the Magnum PI episode "Past Tense" that aired in 1982. It's the 4th episode of the 3rd season and it felt like it was written to include Jack Lord and Five-O.

TC's helicopter is skyjacked and he is forced to land in a local prison and help a prisoner escape. Following the escape, TC and Higgins (who was in the helicopter when it was hijacked) are taken hostage so the prisoner can get the attention of Magnum to finish him off. Magnum works with HPD Lieutenant Yoshi Tanaka (played by Kwan Hi Lim) for clues.

It just seems that a prison break of this magnitude would have been a Five-O matter. And 1982 would have been a perfect time to have a McGarrett cameo as the Magnum series was firmly established by that point. (Meaning it would not have felt forced like some series will do when they're struggling in the ratings.)

I've read rumors that Jack Lord was invited to appear on Magnum, but declined. Does anyone have any additional information about a possible cameo?

That was a good episode. One of the better ones of the third season. James Wainwright (who played the washed-up astronaut in the Five-O episode “Shake Hands with the Man on the Moon”) plays the prison escapee who has an axe to grind with Magnum. I agree this would have been a good episode for Jack Lord to guest star and work with Magnum (though knowing McGarrett I can’t imagine him being very cooperative with a PI, a civilian). But he certainly could have had a cameo and given Magnum some info about the jailbreak. Alas it was not meant to be. Jack pretty much retired once Five-O wrapped. But then Kwan Hi Lim was always a special treat as Lt. Tanaka (a quirky Columbo-type) who would provide occasional help to Magnum. So I can’t complain.

From what I've read in the past, Ringfire is spot on. Lord was asked, but declined.

McGarrett, however, is mentioned multiple times in Magnum. This incudes the first season when Magnum is trying to figure out what happened to a good friend of his. Magnum was 'broke in' to Naval Intelligence, even though Magnum (and McGarrett) had worked there in the past. So there's that. ;)

Yes, the two shows definitely take place in the same universe. I recall a first season episode where Magnum is flying in a helicopter and announces himself as McGarrett, ordering the suspect to stop.

However, I am disappointed that no H50 actor reprised their character in Magnum. Zulu, Herman Wedemeyer, Harry Endo, and Moe Keale all made appearances on Magnum, but as other characters. (Kam Fong also appeared, but understandable that the Chin Ho character wasn't an option).