Corrected entry: The death sentence for cowardice was abolished in 1917, a year before Tommy gets executed.
Corrected entry: The British army abandoned firing squads in 1917, a year before Tomy gets shot.
Correction: Firing squads were still in use as late as 1941, when German spy Josef Jakobs was executed in the Tower of London using that method.
Corrected entry: Martha says that the Doctor recommended her for UNIT. However, in the Doctor Who episode, "The Sontaran Strategem," the Doctor is startled to discover that Martha is working for them.
Correction: Not true, because in "The Sontaran Stratagem" the Doctor is surprised about Martha being a qualified doctor, not about being in UNIT. Watch again.
Corrected entry: When the team plans their mission to break into the mansion, they estimate that there will be one minute, 20 seconds between the time the power is cut and the time the backup generator goes on. When Owen kills the power, an announcement is made that the backup generator will take over in 40 seconds, causing the team some concern. The actual time between when the power was cut and when the backup generator kicks in is one minute, 20 seconds - just as predicted. Oddly, Owen doesn't seem to be moving any faster or trying harder to find a place to hide even though he's under the assumption of only 40 seconds of darkness to work with. A last-minute change to the script, perhaps?
Correction: More likely he sticks to the plan, because mistakes can be made when rushing things that aren't practiced and prepared for. As they say: "The hurrier you go, the behinder you get."
Corrected entry: In the first episode, "Everything Changes," Gwen is told that "Captain Jack Harkness failed to report for duty" on 21 January, 1941. However, in "Captain Jack Harkness," Jack tells Tosh that the real Captain Jack Harkness will be killed in combat, taking down 3 Messerschmidts and getting the rest of his squadron safely back to base in the process the next day. Surely, at least one of his men would have reported that the Captain died a hero. If not, how can he fail to report for duty if he was in the air? (00:39:10 - 00:39:50)
Correction: Gwen asks for information on a living man named Jack Harkness. The original Jack Harkness, the pilot, is confirmed as having been killed in combat - as you say, his squadron would have reported his heroic death. Being confirmed as deceased, there's no reason for the researcher to mention him. Torchwood's Jack Harkness, who took his name and who also served in the military, is the one who was listed as having vanished without trace.
Correction: The last real-life execution for cowardice took place in 1917, but it was not officially abolished at that point. The death penalty for cowardice remained on the British statute books until 1930 when it was finally, after a couple of previous failures, abolished after years of campaigning by MP (and former soldier) Ernest Thurtle. As such it is entirely reasonable that a fictional character like Tommy could have been executed for the crime in 1918.
Tailkinker ★