Audio problem: In the scene at the Palace Hotel Ballroom, when the Blues Brothers are singing their 2nd tune (Sweet Home Chicago), you can hear both Jake and Elwood on the soundtrack but Elwood is dancing down the middle aisle without even a microphone in his hand and his mouth is not moving. There is also a shot during the same song where Jake's singing and pauses do not line up with what we see visually. When he sings "baby don'cha you want to go-oh - -" we see his mouth stop moving, then when he pauses, his mouth is still singing. As a matter of fact, the entire number has mistakes like this and mistakes of continuity. (01:54:20)
Audio problem: At the illegal fight, as Castor and Oxheart get ready to fight, Oxheart's mom says "Don't kill him. Just rough him up a bit." you hear the lines, but her mouth isn't moving.