Continuity mistake: Carly's shoes appear to mysteriously alternate several times between black stiletto heels and black ballet flats in-between shots during the climactic action sequence. This is most noticeable during the collapsing building sequence as well as the scene in which Carly speaks to Megatron.
Continuity mistake: In the first scene with Carly coming up the stairs she is wearing a white cap, when the camera changes to the front view and she is holding the stuffed rabbit the cap is gone. (01:01:30)
Other mistake: In the scene with Richard Nixon speaking to the Apollo astronauts, the TV showing the phone call shows a lamp behind his head, and the seat being right behind him. But if you look at the actor sat there, there is no lamp, and the angle of the camera shows the chair would not be in shot.
Continuity mistake: When the Dreads knock over the freeway sign, the distance between the two green signs keeps varying.
Continuity mistake: When Sam and Dylan are fighting, the clock behind them changes to different times every shot. It starts at 00:40, then 02:25, 00:15 and 11:00 in the following shots.
Continuity mistake: The shot of the Apollo 11 capsule approaching the moon is missing the lunar module, which is then seen attached to the craft in the next shot.
Revealing mistake: In the highway chase scene, when Crowbar knocks down some signs for the other two Dreads to use them as ramps, the simple structure supporting the signs changes to a far more elaborated one when the Decepticons launch from it. The signs are even replaced with actual platforms, much longer, wider, and with different angle and separation than in the previous shot.
Continuity mistake: When Carly shows Sam the stuffed bunny, her hair is curly. Then when she jumps on the bed, her hair is straight.
Continuity mistake: When Sam's parents first show up, we see a shot of their RV with a car parked behind it, on the pavement. When they go to use this car to take him to his interviews it is now on a trailer behind the RV.
Continuity mistake: After Sam and Carly are reunited, her hand keep altering from being very dirty and in Sam's face, and clean in Sam's neck.
Continuity mistake: At the beginning, when Sam receives the medal , his hairstyle (parting) alters .
Continuity mistake: When Sam and Jerry Wang are in the elevator, just after the other co-workers leave, Jerry takes a drink from his milk carton, placing the straw in his mouth, from the top of the straw, down to the hinge section. The shot cuts and there is suddenly less of the straw in his mouth. (00:40:00)
Continuity mistake: In the scene where Sam and Carly are trying to get into the Autobot base, Carly is wearing a black jacket, after Sam sees Bumblebee, she is wearing a brown one, and inside she has a black one on again.
Answer: the weapon is called an "Acid Rust Blaster" which seems to be similar to the cosmic rust seen in the animated series. the rust eats away at the Transformer's metal body.