It's been a while since I've seen the movie but I think the reason is pretty simple: we don't really know where the house is located. We know it's really close, so close that the trio gets to reach it on foot after they get kicked off the bus, but I doubt the house is directly in front of it.
There are multiple reasons why this is likely not a mistake:
- The bus rarely goes directly straight on to the place you're going to. It goes to bus stops that might be close to the point you want to go to, but it's not a given.
- The bus needs to use not only the streets that might not go directly to that point, but also the streets it can use because of city conformation, streets with a single marching direction, etc. So, a smaller number of streets might be available to reach a certain point, causing you to take long turns or weird paths to get to a relatively easy and close point.
- The bus stop is not located near the place you want to go to.
- The place where the bus stopped in the movie is on the side of the house they want to go to and maybe slightly off. For all I (we) know, as stated in the reason 2, the bus could have taken a turn some distance after that unexpected stop and they would have gotten closer. The bus path is unknown to us viewers.
I think that speaking from the point of view of a vehicle, the bus was taking there sooner, not because it chose the most direct path, but because it's faster than a human on foot, and even taking turns and traffic lights it would get you there sooner.
On foot they take another route that is faster because you use paths that are unusable by vehicles: back alleys, stairs, parks, etc.