Goofs

When Major Fawcett is preparing to leave on his first expedition, his wife tells him that she is having another child. When he arrives in Amazonia, he tells his crew that the river will be their home for two years. Yet when he returns to England, the baby is only a few months old.

In many of the scenes the party is going visibly downstream while they are searching for the origin of the river.

Costin is seen in the First World War segment with a beard. British soldiers were not allowed to grow beards.

At about 23 minutes in, one of the workers shouts "Black gold! Rubber!" Rubber and the latex from which it is made are naturally white. The 'black' (usually carbon) is added during processing. 'Black gold' is a nickname for crude oil.

Fawcett was in the Royal Artillery, not the infantry. He would not have been leading an infantry unit in an assault on the Germans.

Percy Fawcett is in the artillery, but his red uniform is actually meant for infantry soldiers. This was intentional, as the director liked the way the colors worked and allowed him to plausibly put Fawcett in the trenches in World War I later on.

If both Percy and Nina Fawcett (played by Charlie Hunnam and Sienna Miller) have got blue eyes, then all their children should have blue eyes too - since that phenotypic characteristic is granted by a pair of recessive alleles, the descendants are homozygous with respect to the eye-colour gene (which is necessarily for blue), hence Jack Fawcett (Tom Holland) "should" have blue eyes. However, 2 blue-eyed parents can have a brown-eyed child if one parent has a working gene HERC2 & the other has a working gene OCA2. Brown eyes are HERC2+OCA2, a combination absolutely possible w/2 blue-eyed parents as persons with blue eyes can be carriers of one of these working genes. See genetics.thetech.org/how-blue-eyed-parents-can-have-brown-eyed-children .

The closed captions are incorrect in a number of places, most egregiously at 1:21:08, when the typist says, "It looks like a war with Fritz [meaning Germany]", which is captioned as, "It looks like a war with France." France and England, of course, were allies during WWI.

Many of the torches used by the indigenous people encountered in the final expedition are modern "tiki torches" and the metal fuel canisters in them are clearly visible in several shots.

At 1:35:42 a soldier can be seen bringing a cigarette up to his mouth, you can see that the cigarette has a white filter. Cigarette filters were not invented till 1925, nine years after the time period the film takes place in.

At around 18 minutes into the movie, supposedly in South America, a British train is shown. The locomotive is in British Rail green with a British Rail insignia on the tender. British Railway didn't exist until 1948.

At 0:18:44 into the film, set around 1906, there is a shot of a locomotive in the countryside, which is a Class 5 Stanier painted in British Rail green with the British Rail emblem on its tender. This logo was originally LMS built around 1935.

During the battle scene taking place in 1918 in which Percival Fawcett got wounded you see German machine gun nest with soldiers wearing Pickelhaube (spiked helmet). The Pickelhaube was replaced in 1916 by the Stahlhelm since this was better suited in the demanding conditions of trench warfare.

(At around 31 mins) There's another raft docked on the shore with one man in it, and another on the shore clearly visible on the left extreme on the screen, leading a horse away. he's dressed in a shirt, blue jeans and cap.

The group sends James away "on their last remaining horse". However, as they floated down the river on a raft, they had no livestock of any kind.

When the group kills the wild boar in the jungle, they don't dress it out, but instead, load it intact onto the raft.

Since they were in desperate need of food at this point, it only makes sense to field dress the boar and do everything they could to preserve it before it started to decay & rot in the hot/humid Amazon climate.

When the group is attacked by natives who shoot arrows at them from the shoreline, one of the men is hit and falls overboard. He is immediately attacked by Piranha, a fish that is common throughout the Amazon.

In the next scene, several of the men are out of the boat, in the water, pushing the boat. No Piranha attack them at any point.