The royal was pictured arriving at the High Court on Tuesday morning ready to give evidence. As Harry entered the witness box, his 55-page witness statement was published - and royal fans were quick to point out a few glaring errors.
In his statement, Harry referred to his father King Charles III as "His Royal Highness," instead of "His Majesty." ITV's Royal Editor, Chris Ship, tweeted about Harry's mistake, writing: "Minor in the scheme of things, but odd no one proofreading the witness statement picked up that #PrinceHarry referred to his father as 'His Royal Highness' King Charles, not 'His Majesty King Charles.'"
Prince Harry made two further mistakes in his witness statement. On the subject of Paul Burrell - Princess Diana's former butler - the 38-year-old used the word "indiscrete" when he should have used "indiscreet".
The segment in question read: "Both my brother and I had very strong feelings about how indiscrete Paul had proven to be with the way he had sold our mother's possessions and how he had given numerous interviews about her."
You may also like
Beyond this, the Duke of Sussex referred to his late mother as "Princess Diana," which, whilst technically correct, is a much more colloquial take on her official title "Diana, Princess of Wales."
The mistake cropped up numerous times, most notably on page 5 of the document where Prince Harry listed her as one of his associates. It read: "Princess Diana, my mother. We were obviously very close. Up until her death in 1997, we were in regular telephone contact when we were not together, especially as I boarded at school. Private information relating to me would have been present in voicemails left on her phone by members of my family or the Royal Household."
Whilst in court, Prince Harry made a number of surprising revelations. Opening up about the paparazzi, the royal said: "Everything felt as though I was under 24-hour surveillance."
He also explained how his panic-stricken grandmother Queen Elizabeth II sent a personal aide to keep an eye on him during his gap year in Australia back in 2003.
Talking about growing up in the royal family and in the public eye, Harry said: "As a child, every single one of these articles played an important and destructive role in my growing up."
What is Prince Harry's court case about?
The case has been brought against Mirror Group Newspapers (MGN) by the Prince and other high-profile figures over alleged unlawful information gathering, including phone hacking. Prince Harry claims that MGM illegally obtained as many as 140 stories published between 1996 and 2010.
Harry is one of four representative claimants whose cases have been selected for trial. The others are Coronation Street actors Michael Turner and Nikki Sanderson and comedian Paul Whitehouse’s ex-wife Fiona Wightman.
Want to keep up to date with the latest stories?