Factual error: When Princess Clara gives Wooldoor the shotgun, telling him that he has to shoot Live Action Cow, she racks the action, thus chambering a shell. Just before he 'shoots' the cow, Wooldoor racks the action again. This would eject the shell, but no such thing happens.
Factual error: When everyone went up in the hot air balloon the sun and the moon are both visible. The illuminated side of the moon is facing in the wrong/other direction from the sun, which doesn't work.
Factual error: When the large Dutch guy tells his story about his life in Holland, there are a several windmills. However, the blades are placed on the wrong side, that way it's not possible for a windmill to turn clockwise, which it does. If the blades were placed correctly, they would still turn to the wrong side, because wooden windmills in The Netherlands are always turning counter-clockwise.
Factual error: In s01e08, "Q and A", when Yelena is playing chess, we see her use the touchscreen which represents the chessboard. However, the bottom left corner is a white square when it should be a dark square. The board is orientated incorrectly, even though the board on the floor isn't.