Victoria police say the animal was spooked when it was clipped by a passing tour bus and then bucked, knocking two of three riders out of the carriage before taking flight through the streets.
One of the riders remained inside the carriage, getting far more than his money's worth as the horse pulled it through streets at top speed.
The remaining passenger was tossed from the buggy when the horse hit another car before stopping on its own.
Paramedics say none of the injuries were serious.
Police are investigating how the initial collision between the horse and the first automobile occurred.