The green and brown silk gown Helen McCrory (Valentina Villefort) wears to Albert's party is the same gown Natasha Little (Augusta Leigh) wears when Byron escorts her to the ball in Byron (2003), and Victoria Hopkins wears on the lawn with Lisa Braund in The Regency House Party (2004).
The beige dress with paisley bodice worn by an extra on the Marseilles wharf early in the film is the same costume Sabina Franklyn (Jane Bennet) wears at Longbourn in Pride and Prejudice (1980), Rachel Fielding (Mrs. Benson) wears in Princess Caraboo (1994), Julie Cox (Annabella Milbanke) wears to read Byron's poetry book in Byron (2003), and Freema Agyeman (Tattycoram) wears on the Marseilles wharf in Little Dorrit (2008). The same costume is also worn by a guest at Fanny's wedding in Miss Austen Regrets (2008).
Jay Wolpert came up with the idea, not present in the novel, that Mondego and Dantes started out as best friends. His logic was that it would work better as a 'buddy' film that turned sinister. Wolpert believed that when a friendship soured, the hate generated was both more terrible and more believable.
After the confrontation with the loyal Jacopo, the count tells him the he will walk home. While walking the streets at night we see the flickering flames of gas or oil lights up on posts along the street... but we also see that the buildings are grandly lit for effect. Though we don't see the actual lighting fixtures, we do see that the light is emitted in powerful and steady streams, something impossible to achieve from the technology of the time period.