The two which are roughly in-line with the front of the cabinet may be for the alternative cash-box bracket, which wasn't used on u.k spec games for long. The black plastic 2-piece cashbox didn't suit an electronic coin acceptor, so after appearing on mid to late System 11 games such as Banzai Run, Taxi, Jokerz, etc, it was dropped from the u.k. production, I've always supposed in preparation for the introduction of 'ECA' coin doors.
The other two may have been temporary attachments for a gun handle, which couldn't be fitted for shipment (not without ordering in a larger shipping carton, anyway). I remember seeing Indiana Jones PBA at Deith Leisure's showroom, with the gun still mounted in the space where the cashbox would sit in commercial use. Salesmen playing it would open the door to launch balls into play, thankfully AIR the game didn't have a safety interlock