Revealing mistake: Throughout the film, the base station radio is not connected to an antenna. In many lengthy shots of the back of the radio we can see the power cord trailing out the back of the unit, but there is nothing plugged in to the antenna socket. This is especially annoying because base station radio problems are a key plot point.
Revealing mistake: The person slamming Blaire's laptop shut at the end is a male crew member.
Revealing mistake: When Viggo pushes the car off the edge and it hits the ground, as it rolls you can see that the engine/transmission, drive shift and tank have been removed. (01:26:00)
Revealing mistake: In the scene with the games console the controller isn't on and it is either not attached to a PS3 or the PS3 is off. You can tell because if the controller was on there would be a solid red light and even if it was just charging there would be a blinking red light.
Revealing mistake: When David Harbour is going to search his place, you see him check his weapon. The picture shows the rounds but all the primers have indentations, showing they've already been fired. (01:21:25)
Revealing mistake: When Alison is holding on to the Titus, Gary tries to save her, and they are seen dangling in the air by the tornado. In the shot of Trey looking out the bank window, you can faintly see wires attached to Alison to make her dangle in the air.
Revealing mistake: At the end of the movie, it's pouring rain but the 2 survivors aren't getting wet at all.
Revealing mistake: When the stewardess asks April to sign her copy of the book entitled "How to Survive a Sharknado and Other Unnatural Disasters..." it's a thin book, and in the closeup as April autographs the page we can read the text and it's actually one of the versions of the "Samsung Galaxy Tab...For Dummies" book, not April's book. Also notice when Kelly Ripa shows April's book to the audience, it's now at least 4x as thick.
Revealing mistake: JR is in the weapon container of the crazy dealer, who passes him some of his goods. JR ends up holding in his right arm a MP5K and an M4A1, which combined are about 5 kilos, but then he passes him an M60 Machine Gun, which weighs over 10 kilos and that the relatively diminutive protagonist just handles throughout the scene gripping it with his left hand and making no effort whatsoever. (00:25:20)
Revealing mistake: At the end the sides of the grave (which Jack just had dug by spade) are too perfect. Only an excavator could get such neat sides.
Revealing mistake: When Tom and Anna were jogging on a dirt path, the woman going in the opposite direction who passes them on the right would be walking straight into the kids (and woman) who were running past them on the left - but the woman on the right disappeared behind Tom's back where the collision would have occurred if she were really there. [Use of a green screen]. (00:29:25)
Revealing mistake: Jim parts his hair on the left side. The stacks of his books on display in the hallway include a photo of him with his hair parted on the right side, but otherwise looking the same. Hair that is persistently parted on one side will not easily part on the other side and lay across the head in the same way. (The image was reversed). (00:25:20)
Revealing mistake: When the tanks are firing on the building near the end, some of the shots of shells hitting the building are reused. (01:35:00)