Revealing mistake: In the first scene where Natalie is checking her phone whilst driving, you can see the gear stick is in the park position and the speedo is on zero, suggesting the car is on a trailer for this driving scene. (00:01:55)
Other mistake: As Ray and Emma are drifting around San Francisco in the speedboat, they come across a Navy ship that just got carried in with the tsunami and is now leaning 20 stories high against a building with water dripping from it. If the tsunami were that high, with the wave having now receded back down to ground level, why are there still fires burning down low? The wave would have snuffed them out. (01:30:40)
Factual error: The sunset is in the wrong direction. The sunset is aligned with the Golden Gate bridge which is in a north-south direction. The sun should be setting to the left on the screen, in the pacific ocean. One can also tell that the shadows of the tents at the emergency camp are too short for a sunset. (01:54:25)
Continuity mistake: When they steal the truck at the mall they have to hot wire it to make it start. Later at the San Andreas fault scene where the road ends, in the same truck, he turns the truck off with the key.
Factual error: In the film, the San Andreas fault produces the largest, most sensational earthquake in earth history that levels both Los Angeles and San Francisco, also creating a massive tsunami that also floods the latter. In reality, and according to many earthquake experts, the biggest quake that this fault could produce is an 8.3 and, being a land and not ocean fault, cannot cause a tsunami. Or as consultant to the film Tom Jordan, director of the Southern California Earthquake Center stated, "I gave (the filmmakers) free advice, some of which they took... But much of which they didn't - magnitude nines are too big for San Andreas, and it can't produce a big tsunami."
Factual error: We repeatedly see Ray Gaines and his daughter, Blake, swimming and thrashing about in crystal-clear floodwater following the tsunami. But floodwater from a tsunami is invariably inky black with thick, churning silt, sediment and debris. The same crystal-clear tsunami floodwater mistake appears in the movie "2012"
Factual error: In the garage of the supposedly earthquake-proof building the walls are all cinder block. This would never be done in real life - the walls would be poured pre-stressed concrete with rebar inside. The same problem in the restaurant that the ex-wife is in - the walls there were also cinder block on the top floor.
Factual error: Near the end, Emma Gaines drives a small fiberglass boat at high speed straight through the plate-glass window of a downtown skyscraper. Plate glass is incredibly dense, much more dense than the fiberglass hull of a boat. On high-speed impact, the plate glass might indeed shatter, but the fiberglass hull of the boat would be utterly demolished.
Factual error: This movie makes the same mistake dozens of others have when it comes to tsunamis. When the water is coming into the bay, Dwayne Johnson says 'we need to get over the crest'. Tsunamis don't have crests nor do they act like they are shown here. The water just 'fills' up like in a bathtub.
Continuity mistake: When the Hoover Dam starts collapsing, we see that the side where Kim, the girl and Dr. Lawrence are goes off first, but in the next brief shot, the other side of the dam appears to go off first and then the trio's side.
Audio problem: When Ray and Emma get in the skydiving airplane, it has a turbine engine, but when it starts makes the sounds of a piston engine.
Revealing mistake: In the scene in the lecture hall, the handrail on the steps to the left of stage makes no sense. If built correctly, which they are not, it would indicate there is a wall behind the back row and the steps are just at or below head height of the people there which makes no sense in this auditorium design.
Continuity mistake: When the helicopter is leaving the restaurant, one of the doors is ripped off. But in several shots, the door is back on. Then off, then back on.
Factual error: While driving the stolen truck, the San Andreas fault has cut off the road, with the opposite (west) side of the fault (the Pacific plate) shifting left (southward). In reality, the San Andreas is a right-lateral fault, and the westward Pacific plate shifts northward relative to the North American plate.
Other mistake: The same section of the Golden Gate bridge is shown being stripped from its suspension cables twice: once when the quake hits and once when the container ship hits bottom and tips over. Also the ship cannot hit bottom, as the depth of the channel beneath the bridge is greater than 600'.
Revealing mistake: When the helicopter is escaping with The Rock and his ex-wife, the helicopter doesn't cast a shadow or a reflection on anything it should have.
Character mistake: Nob Hill is mentioned as the highest point in San Francisco. It isn't the highest point. Mount Davidson is.
Other mistake: At the Hoover Dam scene at the beginning of the film, the dam starts to collapse, when the ground starts to crumble and Kim is running to safety, we see numerous cars on the bridge, most of the cars on the dam have right hand drive wiper blades. This would not be possible since the USA drive on the right hand side. The wipers should be pointing the other way. This is also used for the Golden Gate Bridge scene as well.
Continuity mistake: The older brother cuts his leg on falling glass. The cut in one scene is on his inside left leg by the seam of his trousers, next scene the cut is on the top of his leg and the glass piece is a lot bigger.
Answer: You haven't missed anything. After the successful CPR, Blake is still wearing the two heart necklaces, but a considerable amount of time passes between then and when Ben gives them back to her, so we can presume that the necklaces had fallen off at some point in between. Since Blake had taken it upon herself to wear her sister's necklace with her own, the two chains could have been clasped together (which I've done myself), as if one.
Super Grover ★