Analog watches and digital watches are both explicitly and strictly forbidden. If they accidentally let you in wearing a watch, and then they discover the watch half way through the exam, there is a serious risk they will report you to the AAMC for cheating and you will never be allowed to retake the MCAT, and you will never receive a score.
At my testing center, the computer said how many minutes were left in the current section (or in the current break), and there were multiple wall clocks saying the time of day. The computer did not say the time of day, and I could imagine that some test centers don't have as many clocks, so you may not be able to see a clock from your seat.