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: When Sam is first shown at his new flat and the two small robots appear, Sam has a small argument with them, and takes one of the robots in his hand to put him on the floor, but in between these two shots Carly walks in front of the camera thus focusing our attention on her, but if you look at Sam putting the robot down, there is nothing in his hand. And when it's only him in the shot again the robot comes back. They must have missed adding the CGI maybe because he was in the background of the shot at the time.
Continuity mistake: During the chase with the black GMC's, Mirage has black rims in Ferrari mode. When they finish the chase, he now has chrome rims.
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: *Spoiler* After Cybertron is pulled into Earth's orbit, they show that it can be seen from the earth's surface, pretty much the entire sky is taken up with Cybertron. However, in several scenes afterwards the sky is shown in the background as being crystal clear again.
Continuity mistake: In the highway chase scene, one of the Decepticons knocks down the freeway sign which causes the signs, originally facing the on coming cars, to flip away from them. The other two Decpticons then use the signs to as a ramp to get further down the road. This should be impossible because the signs didn't land that way. When the Decepticons land, the signs are pointing the first way again.
Continuity mistake: Just before Optimus Prime arrives in the street where he kills ten Decepticons in twenty seconds, there is a shot of Sentinel saying "It's our world now!", and he is looking out over that same street. When Sam comes out of cover to take a look at Cybertron, Sentinel is still on the building. But when Sam shouts "Optimus!" Sentinel is gone.
Continuity mistake: In the scene when the characters are sliding down the glass building, just before they shoot the windows, there is a shot where a chair is sliding down along them on the left side. The camera dips down for a moment, and when it goes back up, the chair is gone, even though there is no hole in the building for it to go.