When the Doctor is trying to access patient records on a hospital computer, he messes up his hair so it's sticking up. In the next scene, it's been restyled again.
While running around the hospital many ceiling tiles are missing, having fallen when the hospital was moved, yet no tiles can be seen on the floor.
When the Judoon evacuate the hospital near the end, an exterior shot of the hospital is shown and their ships are nowhere in sight.
When the Doctor and Jones are on the moon, the Earth is a waxing gibbous. However, that evening, they look up at the moon, and it's full. If the moon is full, then the earth would have been "new" or dark.
The Judoon spaceships fire retrorockets to land on the Moon. However, they were in level flight over the surface, and their angular momentum would cause retrorockets to push them *away* from the Moon; they would need attitude thrusters in the opposite direction in order to land.
Near the end, several shots of an oxygen pressure gauge are shown to visualize that they are running out. However, the hospital's medical oxygen supply system gauges do not show the oxygen content of the hospital air, only the pressure within the hospital's oxygen tanks.
We see the Judoon spaceships landing on the moon. The dust they create billows out like faint clouds. In the high vacuum of the moon this would simply race away.
When the Doctor and the plasmavore are talking in the hospital's MRI (magnetic resonance imaging) room, several computers and pieces of metal equipment are visible in the same room as the MR scanner. Since MR scanners use very powerful magnets to image the body, all hospitals keep these machines in rooms devoid of metal equipment. Metal objects can be pulled into the MRI, injuring patients or staff and damaging the machine.
The name of the hospital is Royal Hope Hospital, but the doors and signs all have the initials RHT on them, not RHH. However, UK hospitals are run by Hospital Trusts. RHT could mean Royal Hope Trust.
When Martha looks out the hospital window and realizes they're on the moon, she is still moving but her reflection in the window is completely still.
Considering the Judoon have just walked across the Moon from their ship, there's very little Moon dust on their boots.
When the Earth is seen from the Moon, the Earth is a little more than half full. Later that day, after returning to Earth, Martha sees a full Moon. The Moon should have been just less than half. The Moon as seen from Earth and Earth as seen from the Moon will always be in opposite phases.
When looking out at the Earth from the Moon you can see it's only dawn on London but it was implied that it was lunch time.
While discussing they are actually on the moon, neither the Doctor nor Martha nor anybody else even mentions that they have not only oxygen but also normal Earth gravity, which if you think about it is even more remarkable.
When Martha is checking Mr Smith's heart sounds, she has the stethescope around the wrong way. The ear pieces should be worn with the arms angled forward to fit more snugly into the ear canals.