Guild Wars 2

I just completed the puzzle in Lion’s Arch only to find that the chest at the end was already opened. This has happened to me once before in the zone Mount Maelstrom.
Is this a known bug, and is there any way to get my rewards besides completing the puzzle again later?

Edit: also, the models for the Spear, and Speargun sold by the cultural weapons merchant near the end appear to be swapped.

I also noticed this yesterday. The Pirate Harpoon and Pirate Speargun have their models swapped.

Yup, same here. Any chance to get those right or those skins swap is intended and classes which fight with spear on short range will be hitting their foes in melee with gun?