The final entry in the journal read by Miranda throughout the movie is dated before the very first.
When they turn on the lights in the dark Costco, it instantly becomes brightly lit. In reality, HID lamps are very dim when first switched on and require several minutes to warm up and reach full brightness.
In the flashback scene of Charlie playing the bass, his fingering is completely wrong for the bass notes in the musical cue.
Young Miranda is left handed while older Miranda is right handed.