Visible crew/equipment: At Hoover Dam, after the salute, when Defense Secretary Keller speaks with Lennox and Epps, the reflection of the white reflector screen is visible on Keller's glasses. What's more, the boom mic's reflection is actually visible within the reflector screen's reflection. Two for the price of one. (01:35:30)
Other mistake: When Frenzy attacks Sam, the teenager wears straight leg jeans with a narrow leg opening (not boot cut) and thick-soled Nikes, seen in numerous shots, as he kicks at the Decepticon. After the cut to Mikaela (who finds the reciprocating saw), during which Frenzy has already pulled off the bottom of Sam's jeans, Sam continues to kick and scream just before he gets up and runs. Problem is Sam still wears both thick-soled Nikes, neither of which slipped off as Frenzy maniacally pulled the jeans, with narrow leg openings, from his kicking legs/feet. Impossible even in the best of circumstances.
Continuity mistake: When Sam and Mikaela handcuff all the agents, Sam is wearing a black short-sleeved tee shirt atop a blue long-sleeved tee, before putting on the hoodie. We see the dark tee sticking out when he and Mikaela climb onto Prime. Then moments later, Sam is wearing ONLY a long white short-sleeved (we see it has short sleeves when Bumblebee gives him the All Spark later, through a tear in the hoodie sleeve) tee shirt under his hoodie, when he falls from Prime, when he witnesses Bumblebee's capture and thereafter. (Earlier, after he knocks Mikaela off the moped, from that point on there is a very large hole at the back of his blue and black tees, where we see his skin under the jagged material edges, with no white material seen anywhere. We also see no sign of a long white undershirt at any time when Sam's dark tees go up, during his many action shots.)
Audio problem: Before they leave for Mission City, Lennox tells Keller, "Sir, you gotta figure out some way to get word out..." Then in the next shot, as Lennox shouts, "Let's move!" his mouth stays open - not forming the "m" with his lips to produce the word "move", which we hear very clearly (it looks as if he really said, "Let's go!"). Changes in dialogue are done during ADR and often are not in sync with mouth movements seen onscreen. (01:45:45)
Visible crew/equipment: As Barricade and Bumblebee are fighting, when Frenzy attacks Sam and pulls off his pants, the padded black knee guard (with a white stripe at the top and bottom) that Sam wears on his right leg is visible when he is lying on his back, just after he shouts, "He's gonna kill me!" It's gone in the previous and following shots. (00:53:50)
Visible crew/equipment: When Sam is talking to Mikaela's boyfriend, you can see the camera and crew reflected in the Hummers mirrors. (00:20:20)
Visible crew/equipment: On the way to Mission City, just before Sam spots Optimus Prime, when the camera shows the front of Optimus Prime the camera truck/operator is reflected on the bumper. (01:48:20)
Visible crew/equipment: When Sam tries to hand off the All Spark, the chopper is shot down by Starscream. When the chopper wreckage flies over Sam lying on the ground, the black protective gear is visible between Sam's pants and tee shirt. (02:05:45)
Continuity mistake: When Maggie arrives at Glen's house, in the shot facing him as he shouts at his grandmother, Maggie's open empty right hand is up just as it cuts to the next shot, but now her compact is in her right hand. (00:45:45)
Visible crew/equipment: After the fight with Scorponok, the soldiers are waiting for the smoke cloud to settle. As the camera is moving behind the soldiers, a camera shadow is moving to the bottom left of the screen. (00:44:25)
Factual error: Mikaela hot wires the tow truck by twisting two conveniently exposed and very long wires together. Allowing that this could work at all in a modern vehicle, it can't steer until the ignition lock is turned or removed, neither of which she does. (01:55:55)
Revealing mistake: When Blackout is destroying the base in Qatar, a few Humvees get flipped over, and none of them have engines in them. (00:07:00)
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: 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: When Banachek shows Secretary Kellar the photo of Blackout from Qatar, the photo is a photo taken of the transformer in the Beagle 2 video. It's not the photo Epps took of Blackout. You can tell because Blackout has a box-shaped body and the transformer in the photo has a slender body.
Revealing mistake: At night, when Sam's car is running away by itself, you can see out of the windows that it was filmed in broad daylight. (00:33:45)
Continuity mistake: When Bumblebee "breaks down" on the side of the road, a book appears in Sam's hand that wasn't there before. (00:24:10)
Visible crew/equipment: When Sam and his friend head for the party at the lake, as they drive by the lake and the camera cranes up to show the lake, you can blatantly see the shadow of the camera on the crane moving up. (00:20:05)
Continuity mistake: When Mikela hotwires the tow truck, it has an automatic gearshift. Later, when she is driving and Bumblebee is shooting, look closely, it's now a manual transmission.
Deliberate mistake: If you pay extremely close attention to the scene of all of the Decepticons responding to the small Transformer's message regarding the location of the Allspark, notice that the shot of the police car and the fake helicopter pilot are duplicate shots used earlier in the film.
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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