The grand estate of Pemberley doesn't actually exist. The exteriors of the house belong to Lyme Park and the interiors belong to Sudbury Hall.
Adrian Lukis (George Wickham) and David Bamber (Mr Collins) also worked together in episode 4.3 Damned If You Do... (2015) of Death in Paradise (2011) as Francis Davison and Alan Butler respectively.
Julia Sawalha (Lydia Bennet) & Victoria Hamilton (Mrs Forster) also worked together on Lark Rise to Candleford (2008) as Dorcas Lane & Ruby Pratt respectively.
The aqua pelisse Emilia Fox (Georgiana Darcy) wears at Ramsgate is worn again by Emilia Fox (Clara Copperfield) in David Copperfield (1999). The same garment is also worn by Olivia Williams (Jane Fairfax) at Box Hill in Emma (1996), by Anna Madeley (Lucy Steele) at Fanny's London house in Sense & Sensibility (2008), and by Julie Cox (Annabella Milbanke) at the London party where she meets Byron in Byron (2003).
The sprigged sheer yellow gown with white sleeves Lucy Davis (Maria Lucas) wears at Rosings Park is the same costume Samantha Morton (Harriet Smith) wears at Randalls in Emma (1996). The costume is also worn by Emilia Fox (Clara Copperfield) in David Copperfield (1999)