There was a lot of freakiness in last night's episode of Game of Thrones — including a lot more magical stuff than you've seen in previous episodes. But the weirdest thing might have been this odd little creature, which this appears to be concept art for. Minor spoilers ahead...
This artwork popped up over at WICNet, and appears to come from the official HBO production site or one of the making-of videos — but I can't find it over there. In any case, it's artwork showing an early design for the manticore "with a human face and a deadly scorpion tail" that attacks during a key sequence last night.
There are also storyboards of Samwell's rescue from a White Walker: