I just got the gas mask (already have canteen, torch, sling shot, and shield). How can I select the gas mask so I can use it? I confirmed I have it by going to Inventory, but all four spots on my controller are taken up with the other items. I can't seem to select it like I can my other items.
Select one of the four positions on the controller and hold that side down. Example: Let's say you have the Torch on the left and don't plan to use it for a while, so you want to put the Gas Mask there. Hold down the left side of the cross. The game will pop up a box asking what item you want to map to the left side of the controller. Use the cross portion to highlight that item and then hit "A" to select it. (Unlike other menus in Pitfall, you don't use the control stick to navigate this box for some reason.)