Star Trek: 10 Secrets Of Enterprise NX-01 You Need To Know

Like the NX-01's train car and robotic arms, another feature that was incorporated into the ship's design but ultimately never seen in the series was the aft engineering staging area.

Located at the back of the saucer, this area was usually reserved on starships for the main shuttle bay, but served a different function on the NX-01.

According to Doug:

If you look at the back of the secondary hull, there’s a little platform on the back with a couple of hangar bay doors. That’s engineering staging area, you can also use it to bring in supplies and things like that. But if you take out the center section, there’s a tunnel that goes to engineering and the entire engineering department can slide out and an entire new one can be slid in.

Similarly, four large hatches on the ship's saucer (two at the top and two on the bottom) were intended to be cargo bay doors which, when opened, would provide fly-through space for worker bees or inspection pods.

The idea behind these doors was that cargo and equipment could be placed on the ship by auxiliary craft in the vacuum of space much easier than in a gravity environment. Again, though, these details were carefully thought out and incorporated into the NX-01 and simply never used in Enterprise.