Visible crew/equipment: Stage lights and a boom mic or filming crane are reflected on Miles' helmet when he is about to ride on the track.
Revealing mistake: During the earthquake, when the window-shop bursts, the airbag that breaks the windows is very, very noticeable. (00:53:13)
Revealing mistake: After Miles' track falls down, there's a shot of a wobbling black office building. It is a mere photograph being very obviously moved back and forth. (00:52:56)
Revealing mistake: When Miles is doing his act, he is replaced by an obvious stunt with a different skin color and rounder face.
Continuity mistake: When Stewart is about to save Sam, in the wide angle Sam is lying down, both legs opened wide. In the close-up he is crouching next to the railing. This swaps back and forth.
Continuity mistake: When Sam is saving the last man in the building, he is sitting down with both hands holding the hose. From an aerial angle, half a second later, his position is completely different. (01:16:01)
Continuity mistake: When Stewart and Remy stare at the destroyed building, the sky behind is cloudy and dark, but when the shot focuses on them it is a bright and sunny day.
Visible crew/equipment: A white stage light is reflected on the kettle when Stewart visits Denise at her place. (00:14:29)
Continuity mistake: When Corry rides his bike towards the bridge it's too big for him, the seat being lower than the handlebars. A shot later the kid is way taller and the bike is tiny in comparison.
Continuity mistake: When Denise escapes from the rolling home, she trips and her jeans get covered in dust. A shot later they're clean.
Revealing mistake: When Corry's bridge wobbles, the trees and objects in the background don't, revealing that someone was shaking the bridge. (00:54:10)
Revealing mistake: When the group is trying to escape the office building, a woman in pink falls into the void. Watch when she falls and you'll notice that the stuntman's wig flies off (it's to the left of his head).
Revealing mistake: When the parking lot collapses, there's a brick pillar that not only does it not break into pieces, but it bounces around, revealing it's a hollow light-weight prop. (01:38:26)
Revealing mistake: When the parking lot building collapses, check the right side where the cars are. All along the ground level there's a rectangular strip where the film of the miniature building was pasted on top of the film with the real-sized parked cars. Note how all the debris falls behind that strip, it never falls on top of the cars, as if there was a weird black hole of some sort. (01:37:54)
Continuity mistake: Sam stretches out his right arm to save the man hanging by a girder. A shot later his left arm is stretched. Then a shot later his right arm is extended.
Continuity mistake: Before the mother is covered in glasses, she runs away, her hair covered in dust. A shot later it's clean and shiny. This is because the actress was replaced with a stunt with a wig. (00:58:50)
Revealing mistake: When the California Seismological Institute collapses, the old boss is replaced by a much younger stunt. Also, his sleeves swap between rolled up or not and his tie disappears.
Continuity mistake: A huge chunk of ceiling falls right next to the drunk guy, but the very next shot of him shows not an inch of dust around and the exact lighting as he had before the mess.
Continuity mistake: During the quake, Corry is riding his bike on the bridge and loses his balance, then rests his left hand on the bridge. A shot later it's holding the handlebar.
Revealing mistake: When the cattle truck falls out of the collapsing highway, none of the cows move a single inch nor fall off, revealing the real truck was replaced with a miniature prop set.
Answer: There are two versions of the film. A 'film' version which does not include this scene (and others) and a 'TV Miniseries' version. The miniseries version was made to run over two nights and extra scenes were shot to extend the running time.