Random Trivia For This Title:
- Bill Weasley is played by Domhnall Gleeson, son of cast member Brendan Gleeson.
- M. Night Shyamalan and Guillermo del Toro each expressed interest in directing this installment.
- John Williams, who composed the scores to the first three films, expressed his interest in returning to score Harry Potter and the Deathly Hallows, but was unable to do so due to scheduling conflicts. However composer Nicholas Hooper turned down the opportunity to score the final two films, saying that working on Harry Potter and the Order of the Phoenix and Harry Potter and the Half-Blood Prince took a toll on his family's personal life.
- One of the posters in the café where the trio ends up after Apparating into London is from Daniel Radcliffe's play Equus.
- Jason Isaacs originally considered not returning for this film, fearing that his character's arrest and imprisonment at the end of Harry Potter and the Order of the Phoenix would mean very little if any screen time in the finale. Upon meeting J.K. Rowling, he begged to be let out of prison. She told him "You're out. Chapter one." This immediately convinced him to sign on for the film.
- Frances de la Tour reprises the role of Madame Olympe Maxime (from Harry Potter and the Goblet of Fire) in this film; the character does not appear in the book. She may be a substitute for Viktor Krum (also from the Goblet story), who appeared prominently at the same scene in the book.
- John Hurt's reprisal as Ollivander marks the longest gap - 9 years - since his previous appearance of the series. Toby Jones reprisal as Dobby was second longest, as 8 years.
- Filming the "Seven Harrys" scene was so complex that Daniel Radcliffe counted over 90 takes for just a single shot.
- This time around, Dobby and Kreecher were in most cases played physically on set by their respective voice actors, who the SFX team then had to replace with their CG characters in post-production.
- The only [Harry Potter] film Industrial Light & Magic did not provide visual effects for.
- Having Bellatrix carve "mudblood" into Hermione's arm during the torture scene was not in the original script, but it was an idea that both Emma Watson and Helena Bonham Carter came up with together on the spur of the moment during filming. Filming that scene proved to be very intense for the actors involved (Most of the scene was cut to avoid an R rating in the USA and a 15 rating in the UK). So intense and brutal as it was that Helena Bonham Carter approached Emma Watson right afterward to make sure they were still on good terms.
- Despite individual billing in end titles and poster billing, John Hurt has fewer than 5 lines.
- It had been reported that the film would contain a few scenes of Daniel Radcliffe in the nude, leading to speculation among fans that the film would earn a more strict rating. This turned out not to be the case, although the scene in which visions of Harry and Hermione kissing appear to try to deter Ron give the illusion that Radcliffe and Emma Watson are both nude. In reality both actors wore jeans and Watson was provided with a strapless brassiere so she would not have to be completely topless. Director David Yates said that complete nudity was not necessary as the characters would be partially obscured by fog.