It has been noted that during Mercutio's "Queen Mab" speech in act 1, scene 4, director Franco Zeffirelli took liberties by having Romeo use his hands to embrace Mercutio's face in an effort to shut Mercutio up. Romeo even gently places his forehead against Mercutio's. Critics, such as Courtney Lehmann, have argued that the gesture is "as romantic--in its own subtle way--as the [s]cenes between Romeo and Juliet" (as cited in Hammond, "Do Film Adaptations of Romeo and Juliet Enhance Shakespeare in Contemporary Society or Undermine his Cultural Status?"). Hence, critics also argue that Zeffirelli is calling into question Mercutio's sexual nature, which can be seen as taking a liberty with Shakespeare's actual text in Romeo and Juliet.
Shakespeare did not include any stage directions in this scene. In general, the tone matches the tone expressed by young men or boys fooling around and mocking each other, as can especially be seen in Romeo's response to Mercutio, "Peace, peace, Mercutio, peace! / Though talk'st of nothing" (101-02). Hence, it can be considered taking a liberty to portray Romeo and Mercutio as having a surprising amount of affection for each other; it can especially be considered taking a liberty to characterize Mercutio as homosexual.
However, critics of the above critics, such as University of Brighton scholar Laura Hammond, point out that it may be taking things too far to interpret Zeffirelli as characterizing Mercutio as homosexual. Hammond argues that such interpretations stem from the fact that Zeffirelli is himself openly homosexual, so in Hammond's view, it is a "narrow minded view" to interpret "love [shown] between two men who are like brothers" as homosexual" simply because Zeffirelli is homosexual. Be that as it may, it is certainly legitimate to argue that Zeffirelli's interpretation of Mercutio calls into question Mercutio's sexuality.