While playing with my Earthrise/Kingdom Optimus Prime, I decided to experiment with his trailer and see what I could fit inside it. Turns out that my wooden railway Bertie fits inside perfectly.

Unfortunately, Bertie is the only wooden railway model i could fit in prime's trailer because he just barely fits in the trailer. The other wooden railway models can't fit because of how short the trailer is in height. However I can fit a few Take alongs (albeit with having to open the trailer a bit to fit them inside as the tops of most of them clip the bits holding the trailer together), most Adventures and ERTL models inside it.

Sometimes the best fun with toys is seeing what other toys can work with it.