Fraser says that the explosion could "reshape the Kent coastline" and references both the 1917 Halifax explosion and the 2020 Beirut explosion. Neither of those explosions, which were among the largest non nuclear explosions in history, reshaped the surrounding geography. In both of those cases, large amounts of explosives detonated within the harbor. The ship that Fraser is discussing is deep underwater, meaning that any explosion would be greatly reduced in power by the surrounding water.
Eleanor tells the Prime Minister that the assassins used "an armored drone". They actually used an armed drone.