You can’t experiment with hair
This rule is fairly standard for many shootings because often the actor will do the haircut in which he will be filming for the next several weeks or months.
There is nothing wrong with that. But imagine that you need to film for several months, but ten years. Tom Felton killed his hair by dyeing it white, and Emma Watson went with long hair, although over time her preferences changed radically.
You can’t carry chocolate in your pockets
During filming, Tom Felton liked to stuff his pockets with chocolate from the set, but during filming, he melted, and this to some extent interfered with him and, therefore, filming. As a result, Felton’s pockets were sewn up, and everyone else was forbidden to carry chocolate in them.
You can’t consume high alcohol drinks
Many might think that the rule was invented for Alan Rickman or Michael Gambon, who might drop by the bar after work? No, not just for them. It seems that this rule was first and foremost invented for young actors.
Due to a sharp maturation, the young Harry Potter cast could simply drown in their glory and follow the path that Macaulay Culkin once took. However, this did not help Daniel Radcliffe, who once admitted that, due to his unlimited popularity, he was addicted to what was forbidden for him, but, fortunately, no one was hurt by this, and he eventually quit that bad habit.
You can’t have a relationship
In the early years, Emma Watson was in love with Tom Felton and perhaps he could not have treated her as hard on the screen if they were together.
Also, Rupert Grint and Daniel Radcliffe were in love with Emma Watson, and if all three were not good friends, a conflict could erupt between Radcliffe and Grint. Fortunately, nothing terrible happened on the set, but the rule was violated to some extent.