In the second season episode, "Memories Are Forever", Magnum is called to Washington, D.C. for testimony and is reinstated in the Navy as a full Commander - two grades up from a Lieutenant.

It's possible or at least he may be Robin Masters ghost writer who is actually responsible for his output of trashy best-selling novels. Robin Masters is certainly a real person and we glimpse him from time to time on the show but he may be Higgins' writing partner or just someone he's hired to be the public face of the celebrated author in order to maintain his privacy. It would certainly cast his relationship with Magnum in a new light as this means he's really Higgins' guest, possibly in order to provide some excitement in Higgins' life or give him some inspiration for his writing.

It seems almost certain. The cast experience a curse on a Kahuna statue in 'Ki'is don't lie'. We see several ghosts during the course of the show notably in 'The Woman on the Beach' whilst Magnum hovers between the real world and the afterlife during 'Limbo'. Magnum seems somewhat psychic, his dreams and 'little voice' often providing him with amazing insight and information which he could otherwise not know, even of events from before his birth such as 'Forever in time' and 'Flashback'. It also seems to extend to the other characters, in 'Home from the sea' when Magnum is adrift in the ocean his friends seem to simply sense he is in trouble and come to his rescue.

At least 4, Higgins father was a notorious womaniser who seemed to leave women pregnant throughout the British Empire during a lifetime of military service. During the course of the series we meet Texan cowboy Elmo Ziller, Irish priest 'Father' Paddy and South American aristocrat Don Luis. All are nearly identical in appearance as they are all played by John Hillerman (Elmo Ziller allowing him to use his genuine Texan accent for once) Father Paddy also refers to Soong Lu, another half-brother (or possibly half-sister?) of Oriental heritage.

He is the second son of the Duke and Baron of Perth.

Actually, in one episode, where Higgins won't give up his own title to marry a past sweetheart, Father Paddy mentions at least 2 other siblings besides himself, Don Luis, and Su Ling (Who is female), so the are at least 5 other siblings of Jonathan Quayle Higgins. His daddy got around, or as my Grandad referred to it with my own father, Higgy's father was doing a lot of "Tom-cattin' around!"