Corrected entry: In the scene where Barry is in the rowboat on the lake, there is a yellow Labrador retriever in the boat. Yellow Labs were not bred until around 1900.
Corrected entry: The narrator is telling ('According to a report in the Saint James Chronic...') that Lady Lyndon's father, Charles Lyndon (played by Frank Middlemass), died at Spa, in the Kingdom of Belgium. There's no year mentioned in this scene, but at the end of the movie (a few years later), when Lady Lyndon signs a cheque for Barry, we can see on this cheque the year 1789. The Kingdom of Belgium did not yet exist in 1789: Belgium became a Kingdom in 1831 (21st of July to be exact). (01:37:00)
Correction: Belgium was in theory already a kingdom few after it's independance in 1830. The oath of the first king took place July 21th 1831. before that date there was a regent, the baron Surlet de Chokier. Belgium was already a kingdom, however, no suitable king had been found so far.
Correction: While it's true that the yellow Labrador breed was first recognized by The Kennel Club in 1903, they were being bred before then. However, breeding for a color is different than the color occurring naturally. Labradors varied in colors greatly and yellow shades would have occurred.
Bishop73