I'm gonna be listing all the hints that predate the Pillar reveal from Chapter 234

At first the timeline being fictional is meant to be read as a disclaimer but seeing how its mentioned not once but twice, something is definitely up. The target audience for this series is a bit more mature than your regular shonen. Perhaps its foreshadowing of time being reset.

The text here is slightly hard to read but there are certain words used that are quite shocking when referring to civilisations past. Especially "Luxury Sized Cars" in the D.Gray-Man world the main forms of transportation are horse carriages and trains. Cars don't exist yet.

All of the Noah clan are branded with stigmata, however this scene moments before Kanda defeats Skin Boric we see a huge cross on Skin's forehead, strikingly resembling the Pillar as if the brand wasn't similar enough already.

This is one of the more obvious hints. In chapter 184 Allen's dream takes us to a post apocalyptic setting where we see the same Pillar that was revealed in 234 piercing the sky but not just that we see traffic lights and sky scrapers turned into rubble. Not very 19th century.

Dialogue from Chief Bak as he's exploring the Noah's Ark. He's very impressed by the wildly advanced technology of the transportation device that only the Earl and a select few can control as it knocks current technology of the DGM world out the park despite being 7K years old

Whats crazy is whilst the DGM world as we know it doesn't have things like cars or buses, they have have robots like Sir Komulin. This tells us that perhaps some advanced tech from the distant past/future has remained whilst others didn't.

End of Thread