Just before Murphy asks the shopkeeper about the addition to his sign, he waves goodbye to Father Parker. Notice there is no flagpole anywhere in sight. During closeups after that with the shopkeeper, there is a flagpole and flag right off his right shoulder. It is too close to be missed on the wide angle. Then when he pulls away there is no flag.
After Murphy fakes being drunk in Garrett's saloon and Garrett says he will make sure Murphy gets the building, there is a shot of a wagon going by Garrett's saloon and General Store. Notice the signs. Earlier in the episode Garrett had added his name to both and replaced the saloon sign; now they are back to the old saloon sign and the Garrett name is not under the General Store sign. A little while later after the "Wait for the Wagon" song, the Garrett sign is under the General Store sign again. After the proposal, the Garrett sign under the General Store disappears again. After getting the papers signed, the old Saloon sign is back up. At the last scene after the wedding, the old Saloon sign is up.