Right after the sub fires it's 2nd torpedo, the submarine captain is told there is a ship bearing down on them. He is looking at the Britannic through the periscope and turns to his right to view the approaching war ship. The view changes to the periscope view, and while looking at the Britannic, the periscope turns to the left, when it should have turned to the right.
Vera Campbell is wearing a different undergarment (or girdle) when she wakes up from spending the night with Chaplain Reynolds than when she arrived at his cabin the night before.
The ship did not carry any passengers of any form except for military medical personnel and wounded soldiers.
The only 30 (est.) deaths were when two life boats were launched before orders were given (when still under way), and sucked into the propellers, and propellers were stopped after orders were given. But in the movie, the propellers were never stopped, and the two life boats were sucked in after all the other life boats had been launched.
The ship did not sink at early morning before sunrise, but at eight in the morning.
Britannic's Captain was Charles A. Bartlett, not Charles A. Barrett.
The Britannic's bow hit the bottom while the stern was still above water. The scene showing ship falling to the bottom is inaccurate.
The Titanic is seen going down intact in Vera Campbell's nightmare, however, it actually broke in two. However, only some of the survivors noticed that because the break occurred in a ship section which was already mostly submerged. The fact only became widely known after Robert Ballard discovered the wreck in 1985. Also, it should be mentioned that in the film, Vera Campbell is a survivor of the Titanic and in her nightmare, she sees it going down intact, and dreams and nightmares are often very different than reality.
During Vera Campbell's nightmare, the Titanic's lifeboat say SS Titanic instead of her more widely known designation RMS Titanic. However being a steam powered ship, the Titanic was in fact originally known and advertised as SS Titanic and did not receive the RMS (Royal Mail Ship) designation until later after she'd been contracted by the British Royal Mail. By the time of her ill-fated maiden voyage, the lifeboats still carried the original "SS" designation.
In the film, the second explosion occurred in the engine room, yet the propellers are still rotating afterwards. However, steam engines machines are not easily destroyed and 'Britannic' had two of them, besides a turbine for the middle screw, as well as 29 boilers, so plenty of redundancy.
During the film's prologue, some of the black and white footage seen during the launch of the Britannic is actually from the launch of the Lusitania. The four screws can be clearly seen. The Britannic, like all the ships in the Olympic class, was triple screwed.
In route to the Greek island of Kea, as the passengers are being assembled on the top deck near the lifeboats, Lady Lewis says to Mr. Townsend that her son is still on board. All passengers and crew at this point were on board.
As Reynolds is being drawn toward the propellers just before his death, all three propellers are rotating. Minutes later as the ship begins to list starboard, all three propellers have stopped rotating.
During his debriefing to the ship's personnel, Captain Barrett says that they are bound for the island of Moudros to pick up wounded soldiers. In fact, Moudros is a town and the name of the island is Lemnos.
It is not possible for a WWI submarine while submerged to shadow a steamer for several days. The steamer is too fast.
The correct German confirmation at this time was not "Jawohl, mein Kapitän", but "Jawohl, Herr Kapitän". "Mon capitan" is how the French (may?) put it.
The name of the Captain aboard Britannic was Charles Bartlett, not Barrett.