When Hakeswill gets head-butted by Harper, his head is bleeding above his left eye. But when he goes out and gets knocked to the ground the cut and blood are gone.
When Sharpe kills the French men by a firing squad, one of the men falls with his head to the right. In another shot, his head is to the left.
When Wellington is surveying the dead after the siege, on a wide shot Clayton has his head tipped back over a ledge. When Wellington bends down to him his head is flat in the ground.
Before the storming of the breech at Badajoz an officer encourages the troops by singing 'Heart of Oak'. This is the march of the Royal Navy and given the traditional inter-service rivalry between army and navy it's an unlikely choice for an army officer.
In the beginning, General Picton is depicted as wearing civilian garb in the morning after the end of the siege of Ciudad Rodrigo. Picton famously wore civilian dress at the battle of Waterloo but only because he had ridden hard through the night and arrived before his baggage train. It was by no means his habit and he wore his uniform at Ciudad Rodriguez as a matter of course.
It would have been obvious that Hakeswill had shot Ensign Matthews as he was the only man with a seven-barrelled volley gun.