After Venice and Guy's night out on the town, they say goodnight at the hotel's elevator. A shadow of the boom microphone drops onto the top of the elevator door.
About 12 minutes into the film, Constance mentions to the host that her drink is strong. When the host offers to taste it, she hands him a glass that has less liquid than when it cuts to him tasting the cocktail.
In Venice's hotel room, Guy pours Donnie a second cocktail. Donnie is holding the glass in his left hand, but in the next shot it is in his right hand.