The Gen2 Laser Rod Optimus (which was used for the Year of the Goat Optimus) can store the gun in the front of the trailer (the "cap" that has to be folded down before the trailer can auto-transform into weapons base).

The original toy is so old, it was probably in the original instructions... but I was amazed to see it stored inside the trailer while packed in the YOTG box.
That probably means all the MANY accessories can store in the alt-mode, which is pretty impressive for a trailer-toy that isn't a hollow trailer like Gen1 Optimus.

(and with those BRIGHT pink accessories of the YOTG Optimus, they NEED to be hidden )