- This movie has Jack Sparrow interacting with two historical characters: King George II and Blackbeard. Edward Teach, the historical Blackbeard, died in 1718 at age 38, played by the 68 year old Ian McShane. George II became King in 1727 and the movie has him appearing to be much older than the 44 years he was in 1727 (he's portrayed by Richard Griffiths who was 63). However, Jack referred to Blackbeard's real life death, or more specifically his beheading after the Battle of Ocracoke Island. Backstory explains Blackbeard surviving by bribing Robert Maynard (the man who killed him in real life) into claiming that he slew Blackbeard and took his head. The 1740s-date also explains how both George II and Blackbeard are in their 60s (if Blackbeard faked his death). Ferdinand VI of Spain has a brief scene in the movie and he became king in 1746.
- The Union Flag is the current version incorporating the red saltire of Saint Patrick's flag representing Ireland. This first flew in 1801 following the Act of Union 1800 (previous films used the correct rendition of the Union Flag, lacking the Saint Patrick's cross).
- They use the Blue Ensign, which denotes Atlantic, Pacific and East Indies stations. The correct flag would be the Red Ensign, which denotes West Indies.
- Mechanical tuners were not used for mandolins until early in the 19th century. Peg tuners were the standard.
- During the chase scene, when Jack Sparrow is fleeing from the Palace of King George, one of the pursuing troops uses a pea whistle to raise the alarm. The pea whistle was not invented until 1883, by Joseph Hudson.
- Jack and Angelica jump into the Thames to escape King George's soldiers, and are shown swimming in clear water. The River Thames of the 1740s was a slurry of waste and a fall into the water could — and often did — kill.
- Theodore Groves is referred to in both dialogue and the credits as "Lieutenant Commander". However, this rank wasn't created in the British Navy until 1877. Groves can only be a Lieutenant or a Commander, with the latter being more likely in serving as second-in-command to a Privateer Admiral (Barbossa).
- Several of Angelica's outfits include underbust corsets. Eighteenth-century stays were underwear, and provided support for the bust; underbust corsets weren't invented until the Victorian era, when they were still underwear. An underbust corset worn as decorative outerwear, with an hourglass silhouette, shaped to a point between the breasts, is a modern costume element.
Anachronism Stew / Pirates of the Caribbean: On Stranger Tides