Visible crew/equipment: After Sam is interrogated by Barricade, when Sam knocks Mikaela off her moped the black protective gear that Mikaela wears is visible. It is gone when she gets in the car with Sam. (00:51:05)
Continuity mistake: After Sam knocks Mikaela off her moped, they are both on the ground right beside the moped when Bumblebee shows up, but in the overhead shot as Sam helps Mikaela up the moped is gone, not moved, just gone. (00:51:15)
Continuity mistake: After Sam knocks Mikaela off of her moped, he tells her to get in the car, and she climbs onto the passengers seat, while Sam get into the drivers seat. But in the next shot, there is no one visible on the passenger side of the car. It is best visible just before the lens flare. (00:51:40)
Visible crew/equipment: After Bumblebee locks its doors with Mikaela and Sam inside, the Camaro speeds past Barricade and does a 180° spin. Just before the shot cuts away, as the passenger door first opens there is a perfect view of the back right tire, where we can see the stunt cable attached to under the tire. (00:52:50)
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)
Continuity mistake: When boxer wearing Sam begins to run away from Frenzy, in the shot facing his legs from behind he is wearing blue socks with black stripes, but then it changes to blue socks with white stripes. (00:54:00)
Continuity mistake: When Sam, who is wearing boxers, is running from away Frenzy there is a large tear on his left sleeve, at the elbow. When Sam reaches the fence Frenzy attacks him, and as Sam covers his head with his arms we see the tear is gone from his left sleeve (viewer's right). (00:54:05)
Continuity mistake: When Frenzy is attacking boxer wearing Sam at the fence, Sam's right sleeve at the elbow gets torn while fighting the little lunatic. That large hole disappears when Mikaela arrives with the DeWalt Reciprocating Saw. (00:54:20)
Continuity mistake: Just as Mikaela comes to the rescue with the reciprocating saw, when she holds the saw up in front of her face just before she starts to hack away at Frenzy, the saw's blade clamp assembly is about 8-9 inches. After Sam kicks Frenzy, the saw on Mikaela's shoulder has a different configuration with a shorter blade clamp assembly unit. The blade differs as well. (00:54:25)
Continuity mistake: When Sam kicks Frenzy like a football in the wideshot, the right side of his boxers are torn straight up the leg, but are intact thereafter. (00:54:40)
Continuity mistake: After Mikaela hacks away at Frenzy, when Sam kicks him like a football he uses his right foot in the close-up, but his left foot in the wideshot. (00:54:40)
Continuity mistake: After Sam and Mikaela arrive at the Griffith Park Observatory (the planetarium closed for renovation), when they start to hold hands the distance between the two of them changes from farther apart, to close together, to farther apart. (00:59:35)
Continuity mistake: After Ratchet says: "The boy's pheromone levels suggest he wants to mate with the female", Mikaela scratches her head, but in the shot directly afterwards, her hand is instantly down. There is nowhere near enough time for her to put her hand down again. (01:03:50)
Revealing mistake: When Sam Witwicky's great-grandfather activates Megatron's navigation system, he is blown back. As he falls, you can see one of Megatron's robotic fingers wiggle. (01:06:35)
Continuity mistake: When Scorponok's tail is being examined aboard the transport plane, as it curls itself to strike, Epps jumps back with his hands up near his head, but next shot Epps's hand is positioned on the table for the dramatic near miss. (01:06:50)
Continuity mistake: When the Autobots arrive at Sam's house, we only see Optimus, Jazz, and Bumblebee driving up to the house. But when they transform, Ironhide and Ratchet have appeared and Jazz is nowhere to be seen. Later, Jazz appears from nowhere. Also, when Sector 7 arrives, the Autobots are gone without a trace. (01:09:20 - 01:15:50)
Continuity mistake: When Prime lifts Mikaela up to Sam's bathroom window, there are two baseballs in acrylic display cases and another object (looks like a vintage camera) on the windowsill (beside the tub). Then when Sam runs to that window and sees the Autobots parked as if it were a "truckstop", all those items disappear and are replaced by two small overturned flowers pots. (01:11:55)
Continuity mistake: When Sam's parents begin knocking on his bedroom door, Prime says, "Ratchet, point the light," and nothing is on the bathroom windowsill, but when Ron is searches Sam's bathroom with the flashlight there are two small overturned flower pots lying on that windowsill. The flower pots are gone again when Ironhide asks, "The parents are very irritating, can I take them out? (01:14:05)
Continuity mistake: When Ron (holding a flashlight and lantern) is looking through Sam's bathroom window, saying, "Judy, better call the city. We got a blown transformer...," there is no windowbox under that window, which was there earlier. Yet when Prime says "Ironhide, you know we don't harm humans! What is with you?" the rather large windowbox full of flowers is back up under that bathroom window. (01:15:50)
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)
Chosen answer: There is no reason to think they can't. They simply choose not to. They may feel it's too deceitful.
Actually in this movie (when joining up with bumblebee and the others after they pick up the All Spark) and Revenge of the Fallen, Ironhide uses holographic humans in his cargo bed. Also, Arcee and the twins use holographic drivers at the beginning scene in Revenge of the Fallen.