Continuity mistake: When the girls are having their PE lesson and Poppy is watching them practice their Lacrosse skills, Poppy gets some mud on her face, but in the next shot as she is putting sanitizer on, the splatter of mud is bigger and has changed shape. It is before she has touched it so it wouldn't have spread yet.
Continuity mistake: After Poppy and Kate go to get Poppy's trunk, they both have wet hair. The girls then tell Poppy to get into her uniform before the bell, then, as the bell rings they both still have wet hair. In the next scene, which is consecutive time-wise to this one, they both have dry hair and Poppy looks almost perfect.