Isabel asks Burton to sign her copy of "A System of Bayonet Exercise" and hands him a very substantial book. This writing of Burton's was a 36-page pamphlet.
When praying for the dead while aboard the canoes, the prayer being said is a Christian prayer, mentioning God and Jesus. The chance that the bearers would be Christians is extremely remote. They would be either Muslim or follow traditional beliefs.
Although Larry Oliphant is portrayed as a homosexual, by all accounts he was in real life heterosexual: the filmmakers changed his sexual orientation to create a more dramatic reason for Speke's betrayal of Burton after all they had gone through together.
Sir Richard Burton is depicted as an Irishman in the film, however he was born in England and would have spoken with an English accent.
Burton's scar is wrong. The spear completely pierced his face from one side to the other, with a huge scar appearing on both sides. Also, the angle of the scar is reversed, as the actual scar went from his cheekbone and to the corner of his mouth.
In an scene set in 1854, Isabel is looking at a copy of "The Perfumed Garden" translated by Burton. Burton did not publish this translation until 1886. While Burton's translation was published in 1886, the original was written between 1410 and 1434. (Burton's unexpurgated translation, to be called "The Scented Garden", was still only in manuscript form when he died. Isabel burned it, believing that would help save his soul from damnation.)