I never managed to find the garbage map in my playthrough but went back and found it, was a pretty cool experience! Thanks for telling me the map exists lol. I had a weird experience upon arriving to the garbage island where it un-equipped brad and his sprites would rapidly change between shirtless brad and two wrestling cosplay brads upon walking left or right until i reached a ledge to jump up.
Oh and since you can buy the dismal map, you can go back there after completion where it'll replay the cutscene with Jim and then leave you softlocked walking on the water behind the boat he provides.
And yeah, I figured the platformer part was a joke, thought the pit to the left would be the exit but those kill you in platformers too so at least the save crow was literally tow screens back.