I've heard the following urban legend a few times but have never had it confirmed by somebody in the know.
During construction of Splash Mountain the time came for test runs using sand bags. After multiple successful runs with the sand bags imagineers and engineers decided to do a test run with live bodies. During one of the test runs with live bodies or perhaps on the first run the riders were either thrown from the log or were somehow seriously injured breaking bones and such (the legend usually states it was a collarbone). The test delayed opening for some time in which the angle on the big drop was reduced.
Is this true? Or has anybody else heard it?