Couplings

[Kayakid]

I got the thoroughbred set for my grandson. We set it up on a rug on the floor.  The cars decouple alot from slight rise and dips in the track I think. Is there a fix for the small couplings coming apart?

[trainman203]

Make the track level.  You'll never have level track on carpet. Put the track on the table or a piece of plywood.

  Carpet is terrible for Trains.  Inevitably, little fibers will get into every moving part of the Train.  The locomotive mechanism, the wheels, couplers, Everything.

[Terry Toenges]

I agree with Trainman on both issues.
I had a Christmas layout upon which I had used whit batting. I ended up with locos that wouldn't run because the fibers had built up around the axles. I spent hours with a pair of tweezers, pulling out fibers.
A flat surface is definitely needed to prevent derailing. It you don't want plywood, maybe something like a few thick sheets of foam board would work.