Early in the movie when Victor is shown his sniper rifle its caliber is described as 7 point 62 by 5 point four. There is no such caliber. The correct caliber is 7 point 62 by 54 - or more accurately, 7.62 x 54R with the "R" standing for "rimmed."
When Beatrice and Victor speed away from the home of the driver of her accident, she pulls the emergency brake on his truck. Full size trucks, a Dodge Ram in this case, have the emergency brake pedals to the far left of the driver, not levers like in small cars. Victor would have had to initiate the brake, not Beatrice.
When Victor sends the text 'Did You Get The Key' to Alphonse during the sniper attack, you can see his iPhone is in "iMessage" mode, represented by a blue 'Send' button, which is only iPhone-to-iPhone. However, Alphonse views the message on a generic Android handset, which is not compatible with the iMessage protocol. The iPhone should show a green 'Send' button in that case.
When Victor receives Beatrice's letter, he pulls it from his mailbox. The letter is not formally addressed to him, nor has it been mailed. Beatrice later states she wanted to make sure she put it in the right mailbox. The problem is that Victor's apartment mailbox is the multiple apartment-style mini mailboxes. The mail carrier opens the entire contraption from the top using a key and puts the mail into the individual mailboxes. There are no slots on each box to put mail into without opening the entire contraption. There is no way Beatrice could have put a letter/card into Victor's box without either mailing it, or having access to the entire cluster of boxes.