On the bulletin board when Bea and Cal first enter the Retirement Home, the number of tabs on the Missing Pink Unicorn flyer change between shots.
The flowers in the vase on Benjamin's hospital table is constantly changing between scenes. (The number of pink/white flowers changes, and the color/shade of pink flowers changes, too.)
When Bea's dad wakes up after her story, she throws herself on his chest to hug him. If he had just had heart surgery, this would have caused severe pain and possibly major complications including pulling any stitches apart and major bleeding.
When Bea and Cal enter the Memory Lane Retirement Community (at approx :40 mins), there is a flyer on the bulletin board that says "Wanted! Grape Stopmers" instead of "Grape Stompers." Also, another flyer is headed "Missing Cat," but, has a picture of a raccoon below it.
When Bea and Cal are walking in the retirement home, in the first hallway, Cal bumps into a red fire extinguisher. In the second hallway, you can see a silver fire extinguisher hanging on the wall. Due to fire class requirements, all the fire extinguishers would all be the same.
When Benjamin talks to Bea in the hospital hallway after she's helped Blue out of the rolling laundry basket full of scrubs, it seems that the laundry basket has disappeared like Blue. However, as Bea pulls Blue out of the basket, it rolls down the hallway and is no longer nearby.
When Bea and Cal first enter the retirement home, there is a flyer on the bulletin board that says "There's help!" with a shadow coming down from an empty pair of sneakers. The shadow used in the flyer is an upside down picture of the famous Sasquatch photo.
Ryan's canon tattoo can be seen at various intervals during the IF interviews in the bingo room.
When Bea is trying to show Benjamin the IFs, he claims not to see them, but he looks down when the IFs are small and up when they're big.
On the bulletin board when Bea and Cal first enter the retirement home, there is a flyer for a Pizza Party on October 18th at 7 pm, but the calendar on the wall says November 2019.
When Blue says "Let's go" as he and the other IFs and Bea run up to the stage, his mouth is not moving.