At 7:51, the Handler's nails have red polish on them, but at 24:50, which should be just shortly after in the timeline, they have black polish.
Five (played by Aldan Gallagher) is left handed. But older Five (played by Sean Sullivan) is right handed.
Despite being in a hurry because Carl took Harlan away from her , Sissi had the time to put on a coat and then confronting Carl with a shotgun ? No mother would do that.