Guy who built that shit here and said that, there are 3 glyos connections in the box but only 2 ports. The third connection is the peg from the blaster arm that connects to the arm port. The peg itself is a bit long though, it will only be flush with hollow parts that you can jam it in more(like the tip of a glyan gun for example). But as a connector it does it's job.
On future figures the best way forward would be including two of the cannon arms so you could attach stuff to both arms without needing a second figure. Making a new chest collar/backpack with two or three ports in the back/shoulder area would be awesome as well to get mounted guns, wings, additional glyos arms etc in there.