According to an interview with would-be co-star Karen Allen, Tom Selleck had to turn down the role of heroic archaeologist and adventurer Henry "Indiana" Jones. As she told Variety, "Tom Selleck had been cast, and then it turned out 'Magnum P.I.' got picked up." Allen — who appeared in the original "Indiana Jones" film, "Raiders of the Lost Ark," as Marion and reprised the role for "Indiana Jones and the Kingdom of the Crystal Skull" — said that the folks behind "Magnum" wouldn't let Selleck out of his contract, so he had to ditch the role as Dr. Jones. She went on to say that she met up with Selleck quite a bit later and he revealed how upset he was. "I only know that way after the fact because I sat with him many years later and he told me how heartbroken he was." 

Though Allen didn't specify the occasion for which they met back up, it's possible that their reunion took place on the set of "Blue Bloods"; she guest starred on the 13th episode of "Blue Bloods" Season 4, entitled "Unfinished Business" (via IMDb). Allen played Betty Lowe, a woman who interrupts a press conference Frank Reagan (Selleck) is holding to demand justice for her murdered daughter, Michelle.

In her Variety interview, also Allen revealed that two other actors had auditioned for the role of Indy with her. "I auditioned with Tim Matheson and John Shea. John Shea and I flew from New York together on the same plane to do a screen test, and Tim Matheson was in Los Angeles but I had worked with him just a couple of years before in 'Animal House,' so we were pals." She said she later learned of two more well known actors who went for the part: "I did the auditions with them and since discovered that Sam Elliot and Jeff Bridges auditioned."