The thing that always bugs me about this film

Even though I truly enjoy this movie but the whole time portal thing doesn't make sense. Like the part where Leopold has to go back to his time frame in 1800s he goes back in the day time but when he left his time frame of 1800s(1876)to go into 2001 its nighttime?


Why was Stuart so hooked on time travel and trying to find his great great grandfather Leopold did Stuart want Leopold to end up with his ex girlfriend Kate?