In a non-canonical scene added at the end, Mycroft Holmes refers to a derringer (a single-shot pocket pistol) as a "revolver."
The DVD subtitles consistently misspell the names Melas as "Merlas", Kratides as "Cretites", and Kemp as "Cana"; and the places Wandsworth (Common) as "Wentsworth", and The Myrtles, Beckenham, as "Memerkle's Beckinum".
After Melas is abandoned in Wandsworth Common, the shadow of the mike briefly appears on his back as he walks away from the camera.