The tidal wave that hits Los Angeles is shown breaking multiple times.
Too many times to count, the location of a scene very obviously changes between shots.
Within the same scene, the climactic mega-vortex is simultaneously depicted as a gigantic tornado in LA, and a normal-looking hurricane that hasn't even reached California yet.
Despite the gridlock everyone keeps going on about as people try to evacuate LA, many shots show either empty streets or light traffic flowing normally.
As the tsunami approaches LA, the scenes of the characters escaping on the freeway clearly show normal traffic with hundreds of cars driving TOWARDS the coast.
Several aerial shots of Los Angeles after the earthquake hits show the city completely undamaged.
As the characters try to outrun the tornado in their Humvee, several shots feature them looking back at the twister that's supposed to be right behind them - but the twister is not actually rendered into the scene at all.
The characters repeatedly talk about how the city is descending into chaos with looters everywhere, but the only evidence of this is a single man stealing a motorcycle in an otherwise empty parking lot.
The radio in the Humvee clearly shows the antenna is not installed.
The actors are talking on the radio but it clearly shows the radio back and an empty antenna jack.
While trying to escape the giant tsunami, the characters stop, get off their fast motorcycles, and proceed to run up a hill along a smooth, clear, wide, perfectly rideable path for no reason.
The characters fail to notice an enormous, fully-formed, mile-wide tornado directly in front of them until a dramatically convenient moment.