Just after Higgins is shot, Magnum realizes that Dr Kessler knew that Lena was staying at Robin's Nest as he was part of the conversation held earlier at the hospital. This is in error. The fact is that the relocation to Robin's Nest was discussed in the presence of the police officers and not the doctor. Magnum was given no reason to search the doctor's office.
In the window of the shirt shop, the sign "Going out of business" is misspelled as "busines."
Saul is a former nazi tracker, which means that he is a very determined fellow and well aware of the situation, yet he acts as a helpless and frightened old man.
When Higgins is investigating the intrusion he is readily visible throughout and could easily be seen and killed at any time. A highly experienced military veteran would be trained to avoid such exposure.