The rear wall of Border's kit has many small squares molded on it. In a real Tiger, these are threaded blocks where equipment can be screwed on. Most of them are for the exhaust shields.
But there are four squares, marked in this photo, that don't get used in this kit.
These squares were for a storage tube to hold "star" antennas. Only Command Tigers had this tube. Standard Tigers were manufactured without these four squares on the rear wall.
Border's kit does not allow you to build a "Command" Tiger, therefore these squares should not be present. You should remove them, but Border's instructions never mention it.