A trombonist had put a firecracker into his mute, and at the final note of the 1812 Overture, launched the mute, striking the conductor and knocking him back into the audience. In addition, the bell of the trombone was blown wide open and the slide was launched.
Using a firecracker, the mute hit the conductor (Buster), but did not knock him over. When the equivalent of six model rocket engines were used, he fell forward after being hit. When even more were used, the trombone was practically destroyed, but the bell still did not peel back, nor did the slide launch. Since not even the first part of the myth could be duplicated, the rest could not have followed.  This myth was later tested on "Myths Redux"