The episode begins with Clara asking to meet Robin Hood and the Doctor insisting that he never existed. To prove her wrong he takes her to the late twelfth century where the TARDIS is immediately impaled by Robin Hood's arrow. The rest of the episode sees the Doctor determined to prove that the man is just a myth and he is continually chastising the Merry Men for being too merry.
The episode was a fun swashbuckling adventure and had the manic energy of classic episodes like “Battlefield” while incorporating much of Robin Hood lore. The Doctor uses a spoon to defeat Robin in a sword fight and the pair continually one-upping each other in the archery competition (only to discover later that the Doctor was cheating) are two of the most enjoyable scenes so far in Series 8.
The episode also had a few allusions to early Doctor Who for the keen observers. At one point the Doctor hypothesizes that they may be trapped in a Robin Hood miniscope, which is a nod to the Third Doctor story “Carnival of Monsters.” He also mentions Richard the Lionheart, who the First Doctor met in “The Crusade.” While I have no confirmation on this, the robots in the episode look suspiciously like the robots the Fourth Doctor met in “Robots of Death,” and I am going to assume this was intentional. The episode even saw a cameo by the Second Doctor . . . sort of. While looking through the computer files, a shot can be seen of Patrick Troughton as Robin Hood from “The Adventures of Robin Hood."