There are Three Things Wrong with the scene where Yami/Atem Tricks the Paradux Brothers with His Two Coins.
1= Where did he get a Marker from
2= No One Saw him Writing Down the Symbols on the Two Coins
3= And Finally After Explaining to Everyone on how he knows what the Paradux Brother's Trick was. What's to Stop the Brothers from Switching the Passageway of the Underground on Yami and Friends anyways. So that they would remain Trapped Underground Forever.