Can you legally hide someone you know has a felony warrant in Missouri?

No.

"575.030. 1. A person commits the crime of hindering prosecution if for the purpose of preventing the apprehension, prosecution, conviction or punishment of another for conduct constituting a crime he:

(1) Harbors or conceals such person;

. . .

2. Hindering prosecution is a class D felony if the conduct of the other person constitutes a felony; otherwise hindering prosecution is a class A misdemeanor. " (M.S.S. 575.030)