Gaffes

After Sam and Earl Hill go to all the trouble of exploding the gas wells and barely diverting the rift fault so it won't hit the nuclear reactors, the fault goes on to the Gulf of Mexico, at which point water pours into the fault, which significantly widens it. At that point, the two nuclear reactors must fall into the fault, which would set them off. But apparently they didn't.

Dr. Earl Hill gets rescued from the sinking casino, travels to the command centre, analyzes the crisis and is able to travel across the country and alter the fault all while the rescue team is still rescuing the few survivors (who were with him) from the casino.

During the scenes where the army is setting explosive C-4 charges on the gas field pumps to divert the earthquake around the Red Fields Nuclear Plant, there is a scene where the group (including both doctors Earl and Samantha Hill) gets out of the helicopter, walking towards the pump. Then there is a short 3-step close-up side-view shot of just Dr Samantha Hill walking back towards the helicopter. Then she's again walking with the group towards the gas field pump.

The news anchorman was reporting widespread destruction is Sun Vally and Monument Vally before the volcano and flooding had occurred.

In the opening act, a tsunami is seen crashing down on a cruise ship. This could happen only if the ship was very close to shore. When a cruise ship is at sea, the wave passes deep under the ship without disturbing it.

Whilst at the Hoover Dam, the protagonist's brother is reading the water temperature from the Altimeter and Airspeed dials.

None of the rescue team members are seen wearing any type of masks.

In the last scene showing the now split North American Continent it appears they forgot to show the new CA/NV coastline that was created at the end of the first 10.5 movie. "Los Angeles Island" is indeed shown on the map of North America at the end of the movie. It just looks very small compared to in the previous movie since the map shows such a large area, versus before, when it was showing only California.

The fish flopping on the beach in Waikiki as the water recedes prior to the tsunami are freshwater trout.

At one point, the USGS Helicopter can be seen flying around without its rotors spinning.

When the tsunami is pushing through a group of buildings, the water surges out from one building which does not have any glass in any of its windows, nor any interior items (furniture, etc) being pushed out of the openings, showing it to be a dummy shell.

Despite not being able to animate a single helicopter properly (as seen with the lack of spinning blades, The staff still apparently had enough money to hire out ten multi-million dollar Black Hawks.

As the fault line advances through America, the lava at the bottom of the fault (which is clearly shown from shots of the fault towards the end of the film) should appear as orange or black (depending on how rapidly it was cooling down on the surface) on satellite images, but in the film, the fault is already full of seawater on the satellite images.

Lake Mead and the Hoover Dam are hundreds of miles away from any tectonic fault lines, being in Nevada. Even if a volcano erupted underneath Lake Mead, it would be impossible for the lake's water to reach such a temperature in such a short amount of time.

King's Peak is an extinct volcano, as clearly shown by the abundance of trees growing over its peak. Extinct volcanoes generally never erupt or experience any magmatic activity again.

The nuclear plant has been built on a gas field. This would never happen.