The flags on the front of The Grand Hotel are fifty-star flags, as evidenced by the staggered placement of the stars. In 1912, the flag would have had only 48 stars, which would have been placed in straight rows.
When Richard is finished talking to Robinson in the Gazebo and goes to leave you can see the knees of his suit are muddy and wet from previous takes of the assault scene.
When Richard sits on the bench thinking he has lost Elise and, before she appears, a figure of a girl appears in modern day clothes.
Contributed by: Jasper Kujavsky
When Richard finds his name in the dusty 1912 guest register in the attic, the letter "r" in the last name "Collier" extends over the line into the section reserved for the place of residence, which was Chicago. Later in the film, when Richard, now in the past, signs the register, the entire name is clearly written within the section reserved for the signature.
Contributed by: winegolder
When Rollo opens the door to Room 313 (the room he shares with Maude) and removes his top hat, the boom mic briefly dips into view from the top of the main room's doorway.