There are several examples of literal poison in this story, but it also exists in a symbolic register. The Friar, as an herbalist, understands that not all poisons are inherently bad, but rather that humans are able to manipulate them for malicious purposes—for example, the draft he gives to Juliet doesn't hurt her, but nevertheless causes Romeo's suicide through his impulsivity and rash choices. This suggests that it's not the poison in the bottle that does the killing, but the poison in the mind. After all, there's no outright antagonist in Romeo and Juliet—no single character or entity responsible for everyone's problems—only the toxic, poisonous nature of the feud that brings out the worst in all involved in it. Shakespeare is therefore making a commentary that the true evil in this story, the true poisons that plague us all, are those caused by man, not those that occur naturally.
A simple but consequential gesture, thumb-biting is considered rude and unwelcome in the time of this story, much like giving the middle finger. Sampson and Gregory perform this gesture as a way of antagonizing the Montagues, although Sampson doesn't specify that he's biting his thumb at them outright, but rather in general, as he's hesitant to instigate an all-out conflict, though of course one ultimately ensues anyway.
Queen Mab (symbol)
One of the most striking moments of the film's first half is Mercutio's long, nonsensical rant about the Queen Mab, a tiny, mythical creatures who brings dreams and other fantasies to people as they sleep. The Queen Mab is a symbol of delusions and non-realities, one who doesn't tend to have the best interests of those to whom she brings such things in mind, as Mercutio mentions many scenarios in which she brings about dreams that encourage corruption, greed, and lust. She is also described as insignificant and, of course, is portrayed via a speech that turns into, as Romeo calls it, "nothing." This suggests that Mercutio rebukes the importance of dreams, a fact that stands in contrast to Romeo and Juliet, who believe their fantastic love to be entirely genuine.
Characters overreacting to things (motif)
Many of the characters in Romeo and Juliet are burdened with overzealous emotions; the title characters, whose romance is so fiery and passionate that it sees them married with 24 hours and dead within 72, are the most notable examples. However, others, like Mercutio, who is quick to anger when Tybalt insults him, and Lord Capulet, who becomes enraged when Juliet refuses to marry Paris, are also notable victims of this motif.
Voices of reason (motifs)
In connection with the above motif, voices of reason exist at many points in the film when characters fly off the handle due to passion. When Romeo tells Friar Lawrence that he's in love with Juliet, the Friar immediately criticizes him for jumping so quickly away from loving Rosaline. The Friar will attempt this tone again just before their wedding, when he tells Romeo he needs to love Juliet in moderation, and again when Romeo tries to stab himself in his chambers, and he reminds Romeo of the things he should be grateful for. Again and again, when Romeo is overflowing with blinding passion, the Friar attempts to clear his eyes. The Nurse and Lady Capulet do the same thing when Lord Capulet is so angry at Juliet's refusal to marry Paris that he threatens to let her starve in the street and they stand in his way. These voices of reason are critical to the story's moral because they remind us that the story doesn't occur in a world where these types of overzealous reactions are considered normal; they really are over-the-top and unnecessary. Having more down-to-earth characters to remind their overly passionate counterparts of this is a way of letting the audience know that. Without it, Shakespeare's warning of the dangers of people's rash behaviors would fall completely flat rather than resonate with us.
Romeo and Juliet (Film 1968) Questions and Answers
The Question and Answer section for Romeo and Juliet (Film 1968) is a great
resource to ask questions, find answers, and discuss the novel.