The opening dialogue between Murdoch, Crabtree and Watts discusses the possibility of automated firefighters and uses the word "robot" several times. In fact, the word "robot" was not used in the English language until the play R.U.R. by Karel Capek was translated, over fifteen years later.
When Det. Watts starts taking notes about the crash he clicks the top of his pen to extend its barrel. The first successful retractable pen was marketed in 1950, almost half a century after the setting of this episode.
The detective sharpens the end of the pencil Murdoch hands him with his thumb it isn't a pen.