Try "timer 101 hours". The page title will (very quickly) show "10:05:9x" where x is the 10s digit of the seconds. While the page itself claims it's a one hour timer (59 minutes and some seconds). So the actual time is in there somewhere, just showing up wrong in both places.

It also doesn't seem to let me enter 30 minutes as a timer, but most other minutes times work. So, yes, it's buggy.

EDIT: It's not actually modulo 100 hours, I should note. The display is showing it that way, but since it has the real time stored internally it still counts down. If it were actually modulo 100 hours then it would zero out a 100 hour (or 200 or 300...) countdown immediately, instead these wrap to 99 hours, 59 minutes, and 59 seconds on the first tick.

EDIT: For grins I'd started a 101 hour timer a bit over an hour ago before stepping away from the computer. Despite the display silliness, it actually will run for 101 hours. After the first hour the displayed time rolls back to 99:59:59 and the page title updates correctly. I also noticed that there's a progress bar below the timer, it correctly shows the progress within the 101 hour timer the whole time.