In the comics, Mac’s older brother Dylan has a very brief role as a bit of a jerk in 1988, while Alice is seen at Mac’s house after the initial invasion happens on Hell Day, where she’s freaking out and tries to shoot herself. Mac struggles with Alice and the gun, which is how it goes off, and accidentally shoots Erin. This is different from the show, where Alice isn’t seen after the invasion begins (until the 2019 timeline) and Mac is trying to hold onto the gun when it goes off and shoots Erin.
Dylan, meanwhile, has a much bigger part in the show. Instead of Mac going to her old house in the future and finding a stranger living there — who then tells her the daughter of the former occupants died of cancer — Mac in the show finds her house demolished, and hunts down her brother at a hospital where he works as a doctor. It’s Dylan who informs her she died of cancer. He then takes her home, and the two of them spend some quality time together before Mac is forced to leave in order to protect Dylan. None of this happens in the comics.
