It was one hell of an episode of Game of Thrones last week, with nearly a full hour dedicated to The Battle of the Bastards. There was a lot going on too, so you'd be forgiven for not noticing this minor mishap in the episode, we certainly did.
One eagle-eyed Imgur user did though and pointed out this little discrepancy in Jon Snow's costume. Turns out, Jon Snow's famous sword Longclaw isn't made out of Valyrian steel but rather Valyrian rubber, as can be pretty easily seen in this shot of his jumping on his horse to go after Rickon.
In fairness though, we can let this little flaw go in what was the most incredible battle ever shown on TV. Also, we all know they don't go around carrying actual swords.
Well, at least NOW we know.
Next they'll be telling us the dragons aren't real.