hello!!!! this is why callahan didn’t want to even tell them about the notes!!!
callahan: saw them leave
callahan: did not see them return immediately in the present after they left, which is theoretically what should have happened if they did, in fact, leave
he cannot know if they got back “safely” because he only saw them leave, he did not see where they went
which is why he waited to see if they would turn up
and when they did not
he finally told someone about the letters since they weren’t finding themselves
!