The moon, according to Maddy, looks so large because the moon gets one centimeter farther from earth each year so 85 million years in the past it was 85 million centimeters closer. Actually that would only be 850 kilometers. The moon's orbit is not perfectly round, and its distance from the earth varies by about 40,000 kilometers on a regular cycle.
Maddy explains to Josh that in single stream time travel stepping on a butterfly in the past could change everything in the future. This standard image for the fragility of the time line comes from Ray Bradbury's 1952 story 'The Sound of Thunder'.
The jump-in-the-water hole is the Natural Bridge in the Springbrook National Park in Queensland, Australia. This park is part of the Gondwana Rainforest, so named because the plant biosphere strongly resembles the fossil records for the Gondwana landmass before it split up in the late Cretaceous about 80 million years ago.