Once, Willie and his tractor were late to deliver a load of wool, and he did not secure the bales properly. Unfortunately, due to Willie's carelessness and an overloaded trailer, the load slipped onto the line, causing Rex to crash into it and derail.
Willie's tractor is based on a Ford 5000 tractor. Several other tractors share the same basis.
In the Railway Series, the tractor had headlights, resembling eyes.
Willie's tractor is painted blue in the Railway Series, while it is painted green in the television series.