Title translates to "Here be dragons."
The 3rd boat investigated by Harrow is named "Hiraeth", which is a Welsh word meaning longing or homesickness. Ioan Gruffudd is a native Welsh speaker.
While sitting on the dock with Soroya, waiting for a warrant to search the boat, a cart can be seen beside Harrow that is marked 'Sherlock'. Harrow is somewhat of a sleuth himself, similar to Sir Arthur Conan Doyle's eccentric detective.