MO 28 Spur: The intent here was to treat it as a big Y intersection, but given the presence of independent spur signage you are right that it needs to be a separate file.
MO 112 Spur: OK
MO 134: This is the second decade-old change that has flown under the radar.* My 2007 DeLorme Missouri Atlas and Gazetteer, and present-day Google, clearly mark MO 134 all the way to US 54. Street View shows that was the case through at least April 2009, and then there's a big gap afterward.
*The other is IL 2 in Dixon, which I have already submitted.