The schedule was tight for a complex production. The production team had twelve days to shoot each episode, which director Douglas Mackinnon says was the biggest challenge of the project. The required amount of material was shot for most of the episodes. However, an extra twenty minutes of material was filmed for episode six. Director Matt Lipsey recalls that the team struggled to cut the extra material whilst maintaining the integrity of the episode. Lipsey credits Moffat for not "being precious" over his material during the editing process, and points out that his willingness to cut superfluous material means that he is taken seriously when he argues for something to be retained.