Doc Brown uses some specialized binoculars to verify that Marty Jr. is at the scene according to plan. He flips them open and puts his eyes up to them. When we see his view, a reticle of green corners is placed around the closest individual in view. In the lower right hand corner are three measurements, DIST, gamma, and XYZ. These numbers change continuously. A small pair of graphics at the bottom illustrate whether the reticle is to left or right of center.
As discussed in Chapter 8 of Make It So, augmented reality systems like this can have several awarenesses, and this has some sensor display and people awareness. I’m not sure what use the sensor data is to Doc, and the people detector seems unable to track a single individual consistently.
So, a throwaway interface that doesn’t help much beyond looking gee-whiz(1989).