Just curious, incase I missed something. But in order to activate the teleport in Explorer Society you need to step on the teleport sqm and then you get teleported. This is why you need to first place the item you want to teleport on the TP sqm before stepping on it, so the item comes along to the other place. This is not possible with the mirror though, as you cant walk on it, which means you cannot transport it over to the mainland unless there is some technique that I am missing out on