Why does the current time (on the left side of the progress bar) sometimes exceed the total time (on the right side of the progress bar)?
The current time displays the elapsed time of trackpoints recorded along your activity. This would include moments when you pressed stop on your device or your device stopped recording in response to the absence of movement (if you had enabled the auto-pause feature). The total time figure, however, displays the amount of time that your device was actually recording during your activity. Therefore, if the device had stopped recording at any point, you will see that reflected in the time difference.