Audio problem: In the Russian bar scene the female bartender cycles a pump action shotgun at Dutch when she is holding a double barrel shotgun. Dutch then disarms her, when he turns the shotgun back on her you can hear a pump action shotgun being functioned and an empty shell hitting the floor. Dutch is holding a double barrel shotgun in the scene.
Audio problem: In the scene where Dylan is explaining the Decepticon's plan to Carly, there is a shot of Sentinel Prime moving the control pillar into the tower. During this shot, if you look to the left, you can see that Dylan's mouth is not moving when he is supposed to be talking.
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.