The actual leaf of the ivy differs between long shots and close ups. In long shots, it's shape is more like a maple leaf while in close ups, it is more heart shape.
Ryan holds up a music album that is supposed to be by Lady Die. From the cover, it is actually clearly a copy of Breakout by Swing Out Sister.
Jack poses as a homeless man and removes a toupee from his head after Lady Die gives him the cup. Posing as a homeless man was a spur of the moment decision after he got to the park and realized Lady Die was there, so he wouldn't just happen to have a toupee since he doesn't wear one normally. Also, Die has never seen Jack and he knows it, so he wouldn't need the toupee as a disguise. Although it's true that it doesn't make sense that he conveniently has one on hand, he did need it since Lady Die tends to target younger people to kill and Jack, balding with whiteish-grey hair, would be less likely for her to consider him as a target.
At two points, Ryan, Micki or Jack have possession of the cursed cup. But no one seems anxious to put this dangerous item into the vault and they nonchalantly leave it laying around or take it around town with them.
Micki and Ryan find Birdie's unconscious body in the park and are arrested when police assume they assaulted her. Jack sees them but manages to get away. In the next scene, he retrieves the cup after tricking Lady Di. In the next scene, Jack shows up a the concert to stop Micki, Ryan and Birdie from making an unnecessary attempt to get the cup. No explanation of how Birdie miraculously recovered, how Micki and Ryan got released from custody or much less why Jack would bring a cursed object so close to where the person they have been trying to get it way from was.
Although, however, Micki and Ryan were arrested in the morning (Lady Die mentions it when talking to Jack), so there was plenty of time for Birdie to recover and tell police that they were innocent. After an examination, a doctor could have cleared her to leave the hospital. As for Jack, it doesn't make sense for him to wander around carrying the cup until nightfall when the concert is to take place.