"Entrance into the TIE/Ln Fighter is via a large hatch on the rear of the Pod. It appears to be an engine fairing, but is not. Drawings of the TIE/Ln from SW-IV: ANH indicate this as the primary ingress/egress point. The hinge detail is even finely done in this model kit - note the tiny M4 Sherman Bogie Truck in the photo below. This kind of detail is commensurate with the same methods the original model makers used in building the studio models. It is great to see it replicated by Fine Molds in this release too."

http://www.guntruck.com/TIEFighterReview.html

From what I remember back in the day, it was the toy that started the top hatch craze.

As a kid I always thought they'd get in from underneath.

In the later comics the top hatch is used when ejecting too.

Frankly, I don't really care and popular opinion and more toys have the hatch on top unlike the original plan (which might have been hinged to put in the rod when bluescreening?)