Young Hiro speaks perfect English with the accent of a native American English speaker, yet adult Hiro has the accent of a Japanese person who learned English as a second language.
While in the bar, Kentaro is trying to draw the map from memory. In Hiroshi's office in Tokyo, was a copy of the map from San Francisco. It was covering the wall safe. Instead of trying to recreate it, he should just go get it from the office.