Continuity mistake: The lava is close to the machine, until Fry runs to it, then it's a long way away.
Continuity mistake: When Amy and Leela are wrestling, Amy's leotard changes several times. It varies between pink knee-length leggings and no leggings at all.
Answer: Yes Leela knew from early on that Fry had feelings for her. They were pretending to be a couple in 'A Flight to Remember' from season 1 and Fry tried to get on dates with Leela ever since. She just didn't show signs of the feelings maybe being mutual before some of the later episodes.
Andreas[DK]