Aside from Robbie, we see two other instances of Morbius’ post-Krell inventions, each of which is lacking in its own way.
A tossed orange demonstrates the very dangerous disposal system.
The first is the disposal, which is housed in a cylindrical nook off of the living room. The smooth walls of this nook are covered in the same metallic, cupric material as a short pedestal seated within. When something is tossed into the nook above the pedestal, it is instantly disintegrated in streaks of green-white energy. There is no indication that the device can distinguish between garbage to be disintegrated and, say, human flesh, but even if it can, the utter irreversibility of the action begs for some additional step of confirmation and safety.
Commander Adams discovers Morbius’ hidden door.
The second is the secret door from Morbius’ study to the Krell complex. It is a recessed stretch of wall off of the living room. Adams discovers it accidentally when he approaches and to his amazement, it slides open by dint of his mere proximity. If this is meant to be either secret or secure, it fails on both counts.