When the minstrel begins his song, a pipe player, a violin player and lute player are seen playing behind him (all miming badly). There is no violin or flute on the soundtrack at that point; only what sounds like a harp.
Towards the start of the movie, a man is having his arm bandaged. As soon as the piece of narrative for the character stops, she just leaves it not tucking it in in any way at all and he gets up as if she had finished, leaving bandage just hanging to unravel as he stands up.
The Prince's speech during the funeral includes the line "I...too have lost a brace (i.e. a pair) of kinsmen." In this version, only one of the Prince's kinsmen (i.e. Mercutio) is killed. Count Paris, the Prince's cousin who is slain by Romeo in the play, is left very much alive in this version. This may indicate that the film was trimmed before release, and that the death of Paris was actually cut. The souvenir program given out when the film first played in theatres indicates that plans were originally made for Paris to be killed by Romeo, just as in the original play (there is a reference to "the graveyard where Romeo slays Paris").
When Romeo and Benvolio arrive at the Capulet's ball, Benvolios's love interest is seen standing in one place. In the next shot she's seen walking around and in the next shot she is seen standing in the same place she was before she began walking around.
In the opening fight between the Capulets and the Montagues, Tybalt gives Benvolio a very nasty stab to the eye (area) with his sword. Then, in the next scene, when Benvolio meets Romeo, he shows absolutely no sign of any injury or distress.