In the Hospital files from Atascadero State Hospital, Kemper's full name is stated as "Edward Kemper", as someone probably assumed that Ed was a short for Edward. This is incorrect: Ed in this case is a short for Edmund, and in this context they most likely would've used his full name, Edmund Emil Kemper III.
When digging in the yard, the three skulls are dug-up in individual skull-sized holes, all clean white, angled upward with no other bones visible. The chances of them being discovered and dug up like that are zero.
Cell phones were not around in the 1960s or 1970s.
Considering the fact that Good Friday of 1973 is when Edmund Kemper murdered his mother, and was arrested shortly afterward, it is doubtful that cellphones and laptop computers were available at that time.
A character mentions having a good "gaydar", a word which was not coined until several decades after the 1970s, where the film is set.