Factual error: It is roughly 120-135 dB inside of a C-130, especially one that hasn't been specifically modified. It is so loud that it is painful to be in the cargo hold without hearing protection (besides it being outside of military regulations) and you certainly couldn't have a normal conversation while it was in flight.
Factual error: Set is not the god of death, he is the god of chaos, Anubis is the god of death.
Continuity mistake: Vale's left eye (or possibly both) change to white in his transition/death on the plane. However when he is walking towards others the others before being shot it is his right that is white. (00:28:00 - 00:29:00)
Continuity mistake: When Ahmanet enters the Crusader burial chamber, she walks in holding the dagger with her right hand and then picks up the stone. As the camera takes the close up shot, it is very clear that she picks up the stone using her right hand. When the shot changes, she is now seen holding the stone with her left hand. (01:22:55)
Plot hole: The Mummy would not know where to crash the plane in England to retrieve the dagger from the Abbey as this was placed there thousands of years after her imprisonment. If she did know it was there using her powers she would know that the stone was missing, but she didn't.
Revealing mistake: During the underwater scenes the light appears from below and above but it's underground and should be pitch black, suggesting studio lighting being used.
Factual error: The two protagonists are first said to be 100 miles away from their presumed location. When Greenway exits the helicopter, he notes they should've been 100 clicks (km) removed from their current location. These measurements are very different and therefore the dialogue is factually inaccurate (100 km vs 160 km). (00:09:11 - 00:13:23)
Revealing mistake: During the opening chase scene, there's a few shots where Nick and Chris are running towards camera from gunfire in a few alleyways before they fall through a door. There's two shots where you can see bullets impacting the walls all around them, but if you look in the background, there's nobody there actually firing at them until a few people run into frame at the end of one of the shots. The bullets impacting the walls around them are literally impossible from this angle. Furthermore, during this scene, you can tell from the angle at which the bullets are hitting the wall that there's at least a dozen different shots that should have hit and killed Nick and Chris, but they escape completely unscathed. The staging of the shots is very poor and makes no sense.
Factual error: As the plane is crashing, it is shown in a nose dive, but the actors are shown rolling around in it like a barrel. Everyone should have been piled up against the cockpit bulkhead.
Revealing mistake: When the coffin is dragged onto the plane, you can see wheels that are set in the underneath of the coffin. It's supposed to be a flat bottom and a continuous scene from helicopter to plane, so no time to use a trolley.
Plot hole: When the C-130 transport is falling from the sky, the Egyptian sarcophagus remains lashed to the plane's cargo deck. The crew exploring the wreckage says they are miles from the 'primary crash site' (so that nasty stuff can happen to them without witnesses). The sarcophagus would still be at the primary crash site, along with the remains of the fuselage and cargo deck. (00:32:50 - 00:36:00)