James Chu wrote:
 

Roy put down some cash on the tabletop, "We'll see you
ladies later."

"No way.  We're coming along," Rally said evenly as she
glared at Roy.

Why?  Most of this is pretty good (although I have trouble
imagining Columbo driving his Citroen across half the country
rather than just taking a plane).  But I totally fail to grasp
Rally's motivation for coming along on a police call unrelated
to any kind of payday.  

Sorry, but I think you need a better reason for a GSC-Columbo
crossover, such as the Cats being suspect in a crime,
or believing that a crime being investigated by Columbo was 
the work of one of their bail-jumpers or old opponents, or at least
having them witness something about the crime.  As it
stands you are writing Columbo very well, but the crossover looks
like it's happening for no reason except the author wants it to
happen.