Continuity mistake: In the scene where the Blues Brothers visit the Penguin, the door Elwood opens while running away closes between shots and he is seen opening it twice.
Continuity mistake: When Carrie Fisher first attacks the boys with rocket-propelled grenades at the hotel doorway, they dive for the sidewalk and are covered with debris. As they rise moments later and enter the hotel, their black suits and hats are covered in white cement dust. In the immediate next shot, as they climb the hotel staircase, their hats and suits have no dust whatsoever.
Revealing mistake: During the big chase scene at the end, right before the Nazis accidentally drive off the bridge, the Bluesmobile is seen doing a backflip over their car. Watch carefully as the Bluesmobile first lifts off the ground - an air-ram is visible firing under the car, which causes the car to begin the flip. (Note: This scene has been cropped in some releases so that the air-ram isn't visible, but it is still present in other releases of the film).
Continuity mistake: Spielberg puts the stamp parallel to the paper, but in the close-up it's skewed.
Other mistake: The Nazi leader tells a subordinate to get the license plate number of Elwood's car, but the car was long gone before he would have been able to see it.
Revealing mistake: When the cop car hits the Winnebago to chase the Blues Brothers, we see a puff of white smoke emit from under the cop car as it rolls over that was used to help flip it. The pole can also be seen rolling around near the top of the screen in that same shot.
Continuity mistake: When Carrie Fisher is shooting at the Blues Brothers in the tunnel, there are 3 pipes that run along the left side of the wall that aren't alongside Carrie when the camera angle changes to shots of her.
Continuity mistake: During the mall chase scene, the cop car that flips over is sliding diagonally. When we see the faces of the cops inside, the car is sliding dead straight.
Revealing mistake: When the band starts playing at Bob's Country Bunker, the patrons start to throw beer bottles at them. The beer bottles shatter as they hit the chicken wire. Bottles would not break when they hit chicken wire; they would bounce off and break when they hit the floor. Also, you don't see any of the band members being splashed.
Revealing mistake: During the mall chase scene, a cop car flips upside down and is sliding. At one point, the wires pulling it are briefly visible.
Continuity mistake: At Chez Paul when the sommelier is filling Elwood's glass with champagne, he begins to pour and does so again after the cutaway.
Continuity mistake: Throughout the "Everybody Needs Somebody" song number, pay attention to the band member in the background smoking a pipe. More specifically, watch the smoke coming out of his pipe. Sometimes it's consistent from shot to shot, but at other times, it changes completely. (Ex. When Jake sings "When my soul's on fire," all of the smoke disappears between cuts).
Visible crew/equipment: In a quick, wide shot of the front of the building at the end of the movie, as the cops are trying to break in, the camera and crew are reflected in the back window of the cop car closest to the camera.
Continuity mistake: During the mall chase, a semi-profile shot shows the squad car roll onto its roof and slide with a large panel of orange signage pinned under the roof. Camera cuts to a view of the officers inside the squad car, and there is no signage nor any other debris pinned under the car's roof. Camera cuts back, and the signage is again pinned under roof. Camera cuts back to frontal view, and the signage is gone again.
Continuity mistake: When the brothers are in the fancy restaurant, Elwood drinks champagne from a glass. A few shots later the glass is filled back up again.
Continuity mistake: In Ray's, the keyboard of the electric piano Ray plays alternates between being lit up and not lit between shots.
Visible crew/equipment: As Elwood looks up at Mack in the diner, the camera and lighting rigs can be seen in his shades.
Continuity mistake: The woman in the car trying to shoot Jake has a couple of errors. First, she gets six shots out of a four barrel weapon without reloading. Second, she goes from having the weapon out of the window, to no weapon and driving in one second, where it took at least five or six seconds to get it out and aim it.
Continuity mistake: As Unit 10 slides along in the mall, it alternates from the front dragging on the floor, to only sliding on the roof in close ups on the cops.
Revealing mistake: As trooper Car 10 drives along in the mall, they hit an obviously poorly disguised ramp that disappears after use. Later, it's sent into a spin by unit 70, and you see it on an obvious turntable.
Answer: It's 'Can't Turn You Loose,' often refered to as the Blues Brothers Theme.
rabid anarchist
Also done much earlier by Otis Redding.