Liam Redmond plays the part of "Chief Engineering Rating\\C.E.R. WATTS." However on at least two separate occasions both the ship's Captain Ericson (Jack Hawkins) and later Coxswain Tallow (Bruce Seton - 11th Baronet of Abercorn) clearly call him WATSON.
In any scene where the A.S.D.I.C. is being used and strikes a target, the rate of A.S.D.I.C. pulses increases the closer to the target the ship gets. There is no reason that the A.S.D.I.C. pulse rate would increase, as they are set at a certain frequency that would only be changed by the crew, not by distance to target.
After the British sailors have been depth-charged by HMS Compass Rose, the seagulls converging on the corpses can be seen flying backwards. This is due to the cameraman sailing towards the scene in error when it was shot; the film was simply reversed to give the required effect.