Factual error: In the scene that takes place in Ollie's office after the death of his wife, he is talking to Arthur Brickman who is sitting in front of a plaque for the band Songs:Ohia's album, "Ghost Tropic." We know that the scene is happening 7 years in the past, because Gertie is a baby. "Ghost Tropic" wasn't released until November of 2000.
Factual error: In the scene at the beginning of the movie when Ollie is driving his new born daughter to his father's house in New Jersey, you can see the new Time Warner Center on the New York City skyline. The Time Warner Center was not built until 2003, yet in the movie, he was driving seven years earlier.
Continuity mistake: When Ollie and Gertrude are in the bathroom getting dressed up to go to the music awards, she's upset and fumbling to get her second earring on. She starts to cry and rushes out of the bathroom before getting the earring on, but when Ollie catches up to her in the bedroom, both earrings are hanging from her ears.
Continuity mistake: When Ollie goes to interview for a publicist job towards the end of the movie, Will Smith sits down next to him and they spend several minutes talking in the waiting room. As the camera alternates between the two men during this scene, the turtleneck of Will's sweater changes from shot to shot. In some shots the turtleneck is folded over, so the edge closest to his chin is rounded. In other shots the hemmed edge is sticking up and the neckline is scrunched down. It alternates back and forth several times.
Continuity mistake: Near the end of the movie, during a school production after another child's performance of "Cats" winds down before Gertie's turn, the teacher who stands in as Master of Ceremony for the talent show of the evening is seen lifting the curtain to walk out on stage to introduce the next number. The scene switches to Ollie still running out in the hallway, desperately trying to make a dash for his daughter's school play since he's quite a bit late. Back to the teacher with the head-on shot of the stage, she is now seen quickly stepping out of the curtain again.