>>213608429 (OP)this explains it
https://www.reddit.com/r/JurassicPark/comments/1c7hizn/hopefully_this_helps_some_understand_the_where/
there's also a set diagram where they planned the whole sequence, and it has it too, but in 2d
it's not a mistake, but the film doesn't do a good job of showing you the actual layout