Cats and Trains don't mix!
I learned this from experience this year the first time I reassembled the 4551 Crocodile Train and placed it on the track after many, many years in the Dark Ages. I connected the power controller and started the train slowly. Cool! It's moving and it looked fantastic, but without warning the cats attacked and minifigs and bricks went in all directions.
Did I mention I had built the track on a table above a hardwood floor in the kitchen? I had to move the fridge and the stove to find all the pieces - they were scattered everywhere....
Now, they're oblivious to it, but just be careful the first time....