The carriages are not the same throughout the scene. The seat color changes then you notice the carriage with the black seats is much more ornate than the simplistic carriage that showcases the actors at the beginning and the end of the scene.
In the last 15 minutes of the movie, Priscilla repeatedly kisses Adam while convincing him to marry her. During the first kiss, she leaves a smudge of lipstick above his upper lip. In later kisses, the smudge is missing.
In the beginning, Priscilla establishes herself as a selfishly inconsiderate and controlling woman, making demands on Wendy's time at all hours via her cell phone, but when she leaves town again, Wendy isn't phoned even once.
It is not explained why the choral group singing in Priscilla's apartment building (bursting into song when elevator doors open) appears later in the Christmas tree lot. It is also not explained how they - full of the Christmas spirit - shove their way unthinkingly and rudely into the elevator (while singing), trapping Adam who is obviously trying to follow Wendy out.