Corcoran and O'Brien is about to explain the solved murder of the dentist, but smugly insists that they have arrested nobody. Maguire says "The two of you're are grinning like a bunch of Cheshires". Thus referring to the fictional character in Lewis Carroll's "Alice in Wonderland". However, this book was not published until 1865. During the series' intro it is hinted that it is supposed to take place in the year 1864.