The unnamed man in his seventies had been sitting on the large-scale model locomotive in Wilmcote, near Stratford when it left the tracks and fell off a garden wall.
The OAP train fan was left trapped under the model train for 30 minutes until ambulance crews and firefighters arrived and were able to release him.
He was airlifted to University Hospital Coventry and Warwickshire and is said to have suffered abdominal and pelvic injuries.
It's not known when the garden-based train schedule will be back on schedule.