I believe these are the brackets you are referring to. It appears there is tape on the end of the one closest to the can.
Hard to imagine they would say "(2) metal brackets with duct tape" and then only show one, basically (or one and a half) though I agree that there's the gas can and there's two metal brackets so that's probably them.
The vision I had when I first read that statement about the brackets was that they were partially wrapped with duct tape. Some people wrap the bottom part of the bracket with duct tape for a padding (like if you're hanging something on them that you don't want to get scratched). Kind of mickey-mouse but it works. Looks like I may have been wrong, though.