Lisa claims that she cannot return to the present as her power depends on electricity and there are no powerlines in Farber County in 1895. However, she had no such problem when she travelled back in time to the 12th Century in the previous episode Dead Can Dance (1995).
Wyatt and Lisa claim that if Gary's great-great-grandfather Red Brick Wallace dies, his parents and grandparents will never be born. However, it would only be his father, grandfather and great-grandfather who would never be born.