The films of Olivier, Welles, Brook and Kurosawa constitute the most important material upon which this study has been based. It is only right, therefore, to point out that certain variations were noticed in the prints available for viewing. Not only were there omissions which reduced the duration of most prints from the advertised time lengths, but in some cases sections of film had been replaced in the wrong sequence. Only once was it possible to see a print of Kurosawa's Throne of Blood which included the prolonged and very significant sequence of Washizu and Miki (the respective Macbeth and Banquo figures) as they ride into and out of the forest mist early in the film's action. One print of Olivier's Richard III was 18 minutes short of its advertised length. These variations had to be accepted as inevitable disparities.

Welles's Macbeth and Othello present special difficulties because Welles does not seem to have declared one particular version of either film to be definitive. The original version of Macbeth is believed, according to the Folger Shakespeare Filmography, to have had a running time of 105 minutes. That original 1948 version was withdrawn because of its faulty sound-track and re-released in 1949 and 1950 with a recorded sound-track and a shortened running time.