There have been several different removable dials seen in safemaking going all the way back to when the combination lock evolved from the lever lock during the mid 1800's. There were numerous examples of wheel locks with removable key dials. In modern times the US made Star and Major round doors had removable dials. There are also many examples of removable dials seen on bank quality locks but these unlike the Star and Major were not intended to be removed by the user. If the cannon movie is the one I remember it was based on a true story. Regarding the water filled method twice in my career I have opened safes that had been filled but unsucessfully opened with explosives. Both of these attempts occured prior to the DeNiro movie ,can't remember the name, where that method was sucessfully used.