A couple of snippets from our source. Some of these are already known but we've included them all here.
Higgins is also ex-MI6, but was disavowed.
There's still 2 dogs like in the original show.
Magnum still drives a 308 GTS Ferrari like the original, although Higgins doesn't want to let him use it.
Magnum has some history with a woman named Hannah. It didn't end well, but she was his CIA contact and girlfriend for a mission in North Korea years ago that Robin uses in his new book. There is a Plot Twist here.
Someone dies and someone is shot in the pilot.
Magnum and Lt. Tanaka of the HPD do not get along - some backstory there.
The pilot mentions FIVE-0, they are both shot in Hawaii, and the showrunners are from Hawaii 5-0, so there may be a crossover here. No way to tell at this early stage.