How does Bruce Wayne, who doesn't even have shoes, get from an Asian desert all the way to Gotham, which has no bridges, without being seen?
He's Batman? Honestly, I have a hard time seeing why people get so stuck on that first part. He's supposed to be the most resourceful man on the planet. Getting back to the US doesn't seem like it would present any special obstacles to someone like him.
As for Gotham itself, it seems like the effort is mainly focused on stopping people from getting out, not getting in.
First of all...he was not just sitting in an asian desert. It was sitting next to a fairly large city.
Secondly, the people watching Gotham were more concerned with people getting out rather than looking for a single man trying to get in. A city is a big place...getting in ain't hard. Remember, Wayne Manor is in the suburbs...thus his equipment would be out there. Finally...most modern cities have all sorts of maintenance and supply tunnels underground. Bridges and major tunnels are just for road/foot traffic. Its a foregone conclusion that there are tunnels across the river that house fibre optic cables, gas and water mains etc. Hell, back in the 90s here in Chicago they managed to flood part of downtown because, while doing maintenance work, city workers accidentally punctured a century old tunnel under the Chicago river that everyone had forgotten about.