When Brown and the Queen are in a boat on the loch, from a distance, the vessel has a red flag flying aft. In following scenes shot in the boat, the flag behind the Queen is blue.
At Osborne House, Brown is standing on the upper terrace, below the second story grand hall windows, with the Queen's white pony, ready and waiting for the Queen's call to ride. From the upper terrace level, he is standing on the horse's right. As the Queen walks through the grand hall with her daughters, she notices Brown standing and waiting through the window, and pauses at the window to observe more closely. Now Brown is standing on the horse's left, which appears closer to the window because of the angle of the shot.
Disraeli speaks from notes in Parliament, and again at the end of the film. In real life, Disraeli delivered all of his speeches, including those several hours long or involving complicated statistics, from memory. He warned younger politicians against using notes as a crutch.
When the Prince of Wales recovers from typhoid, the Queen commands that a Mass of Thanksgiving be held at St. George's Chapel. Queen Victoria was a devout low-church Anglican/Presbyterian in England and Scotland, and never would have ordered a mass. A Church of England Service of Thanksgiving was held at St. Paul's Cathedral.
When Victoria first receives Mr. Brown, she is writing with her left hand. While Victoria is presumed to have been naturally left-handed (she painted with her left hand), she definitely wrote with her right hand, a forced conversion that was common well into the 20th century. Victoria is later shown crocheting with her right hand, something she almost certainly would have done left-handed.
When Victoria is shown on her first horse ride with Brown, she is riding Western style. English women, especially of the aristocracy, never rode this way. Sidesaddle was the accepted way for women to ride at that time.
The Prince of Wales, referring to his mother, says, "She's having a bust cast of him [Brown] in Nero Marquino marble." Busts of marble are not cast, they are sculpted. Only bronze busts are cast.
John Brown wears greenish blue tartan throughout the film, except during his dance with the Queen, when he wears red tartan. Under normal circumstances, a highlander would only wear his own clan's plaid, even for a royal event. As a royal servant, he would be expected to wear royal tartans. The red is Royal Stewart, the green may be Hunting Stewart.
When reading the newspaper story about Brown, Henry Ponsonby mentions that Brown listened to "Auld Lang Syne", performed by Robert Burns himself. Burns died in 1796, 30 years before Brown was born. Ponsonby, who made the statement humorously, is referring to a seance.
In 1871, after the Mass of Thanksgiving at St. George's, Windsor, for the Prince of Wales' recovery from typhoid, all the royal carriages bear the monogram "VRI," for Victoria Regina Imperatrix (Victoria, Queen and Empress). The "I" was added in 1876, when Queen Victoria was named Empress of India.
When the brothers are drying off after their swim, a windsurfer is visible in the background, just to the left of Archie.
A maid tells Brown about "Lord Tennyson". Alfred Lord Tennyson became a peer in 1884, a year after Brown died.
Benjamin Disraeli is shown as Prime Minister in 1866. Disraeli became Prime Minister on February 27, 1868.
Immediately after "1867" appears on screen, a speaker in Parliament raises the question of the "Disestablishment of the Irish Church." Known officially as The Irish Church Act 1869, Parliament passed it during William Gladstone's administration, which was after Disraeli's first ministry (which ended 1 December 1868) and before his second ministry (which began 20 February 1874).
Toward the end of the film John is writing in his diary. He finishes writing, closes the diary, then rushes out of the room. BUT, anyone who has ever used a steel pen (such as our Mr. Brown!) would NEVER have just closed the journal. That person would have allowed the ink to dry, or blotted the ink. Otherwise, the ink would have smeared and created a mess.