Like many other times when filming with Bradley and Colin scenes have to be re-filmed and repeated multiple times to get them right. Sometimes it’s the directors choice - to get /just/ the emotion he wants in their faces, to get the right shot of the two. Sometimes it’s the two goofing off and pulling faces - often trying to get the other to laugh. But when filming scenes for that fourth episode in season four - there was one that the boys continued to mess up. 

Something about Merlin/Colin tackling a nearly pant-less Arthur/Bradley had the boys doing it over…