When discussing a scene from one of Robin Master's book Higgins points out that the 4 precision shots with a semi-automatic in a short period of time is not realistic. She goes on to say that with an automatic, it would be possible.
However no one uses automatic weapons for precision shooting as automatic weapons, which although they have a higher rate of fire, are inherently less accurate.
Higgins, an experienced former MI6 officer, would not be so unfamiliar with firearms to make this mistake.
When Higgins tells Magnum the security code she says it's Robin Masters birthday, August 4th. However, she fails to tell him if it's 0804 or 0408. A Brit like Higgins think of that date as 0408, where as Magnun would assume it's 0804.