Idk if this is intentional but when you hit the signpost before the rusty ruin act 1 boss, when it spins, instead of showing shadows normal signpost picture, it shows this. I don't see it anywhere else. It looks pretty cool.
It's the beta signpost I made originally before I remade the final one for release. As Nack's signpost is a different object compare to the real one, it still has the beta Shadow in. Consider it an easter egg of sorts ^^