The coffee stain on the cover of the forged case file changes between shots of the file's creation.
Peter speaks while the music box is being recorded, but his voice is not heard when Mozzie later plays back the recording.
When Fowler walks behind Diana's car, he walks completely up onto the sidewalk, but a few scenes later he is shown to be behind her car again.
As she exits Neal's apartment Alex's hand jumps from inside her purse to her shoulder between shots.
When Mozzie tries to decode the musical code, he uses his synthesizer. The model is a Minimoog and it's a monophonic synthesizer, i.e. it can't play more than one note at a time; however, when Mozzie is frustrated, he hits several keys at once and we hear several notes at once. This is not possible with the Minimoog.