Continuity mistake: When Agent Simmons takes Mikaela and Sam into custody, the headrests in the SUV vanish when Prime shows up. The driver's headrest is visible just after they enter the car. When Sam says, "My car had been stolen, from me, from my home," and when Simmons asks, "What do you kids know about aliens?" the headrest behind Sam is visible, among other moments. (01:19:00)
Continuity mistake: When Jazz uses his magnetic hand to remove some of the guns from the Sector 7 people, the guns fly into his palm, but in the next shot, his hand is down and there are no guns in his hand or on the ground. He couldn't have put his hand down or thrown the guns away that fast between the shots. (01:22:00)
Continuity mistake: Mikaela begins cuffing the undershirt/boxer wearing Agent Simmons arms around a post in the wideshot, then it cuts to the close-up, as she handcuffs the dark suit wearing right wrist of one agent to the dark suit wearing left wrist of another agent. Then in the two following shots we see that she and Sam have actually just cuffed the undressed Agent Simmons left wrist to the dark suit wearing second agent. (01:24:00)
Continuity mistake: After Mikaela and Sam walk away from all the handcuffed agents, when we hear an Autobots shout, "Optimus! Incoming!" the railroad crossing post is visible behind the Autobots, but Agent Simmons is not handcuffed to it. Then, when we hear, "Roll out!" Agent Simmons is handcuffed to that post as he should be. (01:24:20)
Continuity mistake: When Optimus is holding Sam and Mikaela during Sector Seven's search for them, Mikaela falls, and in the shot facing up Sam hangs onto Optimus with his right hand and grabs her with his left hand. In the next overhead shot Sam now hangs onto Optimus with his left hand and holds Mikaela with his right hand. (01:26:10)
Continuity mistake: When the SUVs arrive at the Hoover Dam, the lead car pulls up to the curb and the doors open directly in front of the first elevator tower (there are four, which are seen in overhead shots), on its right, with the two Nevada intake towers well ahead of the SUV, on its left. Next close-up, however, as Sam exits the SUV the vehicle is now parked farther up the road, directly in front of the Nevada intake towers to its left and closer to the second elevator tower. Note the yellow pedestrian walkway markings (leading to the Nevada intake towers) the SUV is parked on in the second shot. (01:34:25)
Continuity mistake: As we are hearing Prime explaining, "They're a young species, they have much to learn," we see S-Seven's SUVs pull up to the curb at Hoover Dam and the doors open, right beside the vertical guardrail posts with the horizontal beams. In the next close-up, all of the horizontal beams have vanished. (01:34:25)
Continuity mistake: At Hoover Dam, when the soldiers salute Keller the clock reads 10:00, then as Keller, the soldiers, Maggie and Glen walk away in the background, when Simmons tells Sam that they got off to a bad start the clock reads 11:35, and next shot when Banacheck interrupts it reads 11:43. Also when Simmons talks to Mikaela and Sam the word "Nevada" is gone and it only reads "Time" under the clock. Then when Banacheck says, "Come with me, we'll talk about your car," the word "Nevada" is back under the clock. (01:35:25)
Continuity mistake: At Hoover Dam, when Sam tells Banacheck the terms of his cooperation (which include expunging Mikaela's juvenile record), Mikaela's high-gloss lip gloss disappears in her close-up, then reappears. (01:36:00)
Continuity mistake: While standing in front of a frozen Megatron, after Banacheck explains that Sam's great-great-grandfather made one of the greatest discoveries, Sam and Mikaela are shoulder to shoulder, but in the next back shot they are 4-5 feet apart. They're beside each other again in following shots. (01:37:20)
Continuity mistake: When Simmons leads the way into the room with the old Army radio console, he pushes open the massive doors with Keller and the rest behind him (we see the very distinctive wall opposite those doors). When Frenzy pays them a visit at those doors, just as Simmons shouts, "Burn, you little sucker!" in the overhead shot, that side of the doors (in the hallway) is once again visible, only they look completely different now. (01:47:25 - 01:49:15)
Continuity mistake: When Bumblebee's legs are destroyed, as Sam leans over in front of him and asks if he's alright, Sam wears blue patterned boxers, but when Lennox runs up to Sam, who is standing on the tow truck helping Mikaela hoist Bumblebee, Sam's boxers are grey (as seen between his white tee and jeans). Then, when Sam is on the roof running, after the chopper is hit, his boxers are blue patterned. (01:53:45 - 01:57:10)
Continuity mistake: Odd how Mikaela is not wearing her stud earrings when Sam leaves her to go to Bumblebee and she spots the tow truck across the street, and also when she arrives in the tow truck and says, "Sam, help me with this." Yet, she is wearing them between those shots, when she breaks into the tow truck and hotwires it, and in the prior and following shots. (01:55:25 - 01:57:25)
Continuity mistake: When Mikaela is telling Captain Lennox that she'll leave as soon as she gets Bumblebee out of the area, watch her hair. At first, her back is to the camera and her hair is perfectly smooth but when the camera is facing her, her hair is extremely messy. (01:57:55)
Continuity mistake: During the final battle, Sam and Mikaela tie Bumblebee down to the truck. When Mikaela says, "No matter what happens, I'm really glad I got in that car with you," Bumblebee is gone. (01:59:00)
Continuity mistake: After Sam takes off running with the All Spark, heading for the building, Prime is shown driving down the street towards a collection of garbage bins. In the next shot, before Prime hits them, all the garbage bins are set up very differently. (01:59:45)
Continuity mistake: When Optimus Prime first arrives in Mission City, he knocks over a few garbage cans, and a few pieces of paper gets stuck on the grill of the truck. But in the next shot, the pieces of paper are gone. This is not because he slowed down, because the grille is out of shot for less time then it would take paper to fall off. Not only that, but the air blowing at the paper would make sure it sticks on. (02:00:00)
Continuity mistake: After Megatron says to Optimus: ''Then you will die with them!'', Megatron throws Optimus away, and the latter one heavily damages a car, and two others skid sideways in order to brake in time. Two other cars remain parked. But in the shot where Optimus gets back up and draws his gun, only one car remains. Even if the two cars that stopped just before they hit Optimus drove away, there would still be two parked cars and one heavily damaged one. (02:01:00)
Continuity mistake: During the final battle, Sam rolls on the pavement and reverses direction as a jet-bot lands and transforms. The next wide shot shows Sam scurrying alongside the passenger-side fender of a black Mercedes sedan as another black car is tumbling over the Mercedes' hood, its doors wide open. This same moment repeats in the next shot, from another angle, but suddenly Sam isn't at the fender of the Mercedes- he has vanished. The angle changes again and the same moment repeats a 3rd time, and Sam is still missing. Then, a closeup shot is looking up past Sam as mayhem rages above, and the black Mercedes he huddles against is suddenly a red car. (02:01:20)
Continuity mistake: When Mikaela has Bumblebee at the back of Mike's Towing truck, she drives down an alleyway, and when she stops the truck in the close-up there is a trashcan and other debris between the front two tires, which vanish in the wideshot. (02:02:25)
Answer: Because the Decepticons didn't know where Megatron ended up for the last 100 years. Bumblebee arrived on Earth as a scout to check out for any clues, found the glasses on Ebay, signalled the other Autobots, which prompted Blackout and Frenzy to investigate the base in Qatar, which lead to Blackout downloading the base computers and Frenzy hacking the computers aboard the aircraft later leading to the discovery of Megatron's whereabouts.
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