Factual error: A "wonky" whistle doesn't sound like a slide whistle, it should sound like a weakened version of the correct whistle mixed with the hissing sound of steam. A "wonky" whistle would also leak steam constantly instead of being blown like a normal whistle.
Plot hole: Thomas or his crew should've realised that the whistle was "wonky" the first time it was blown. Also, Thomas and his crew should've waited for the whistle to be fixed, instead of leaving while the workmen were on top of him.
Continuity mistake: When Flynn sprays Edward, the water goes over Edward, but somehow his driver gets wet. And when Flynn sprays Gordon, the water is seen hitting the platform and Gordon's tender. Later, the water is seen hitting one of the coaches.