Plot hole: In the last car-chasing scene, the timekeeper had switched his car to chase them, then how could Justin Timberlake get the timekeeper's salary (a day's time) from a car that the timekeeper picked up from the streets?
Suggested correction: I think it is the car of another time keeper. Hence, it may have a time transfer system.
Continuity mistake: Toward the end of the movie, after the TimeKeeper dies and Timberlake and the girl start running toward the TimeKeeper's car for more minutes, in the background, as they are running, the TimeKeeper's body has vanished.
Continuity mistake: When Will leaves Dayton for the first time, the car leaves Zone 12. Later it goes through Zone 8, and eventually arrives at Zone 4 (New Greenwich). But when the authorities are first checking the security footage of Will on the bridge, they have a Time Zone map on the wall, and Zone 12 and 4 are next to each other, with Zone 8 in a different direction.
Plot hole: Conceptually, there is no point in working unless you earn more time than it takes you to commute to work, work, and commute from work - literally living day by day. We are given no information on why Will's mother, on her commute home, has only 1.5 hours to live. Unless her work didn't pay her at all, why would she work that day?
Suggested correction: You described the plot perfectly, poor people have to work just to live day to day. Rachel, Will's mother, had to pay off a 2-day loan, which is why she was left her with only 90 minutes. Then the bus fare increased, which she wasn't expecting, from 1-hour to 2-hours, which explains why she had to walk home.
Revealing mistake: When serving on the bridge, there are multiple shots where skid marks from previous takes are visible. (00:44:20)