At least three different phones were used as Albert's smartphone, as the make and models change throughout the story.
In the opening scene, to make sure the car goes from left to right in every shot, one of the shots is flipped. The low angle flipped shot subtly shows the car driving on the wrong side of the street.
In the Prep Room, the IV bag is in shadow in one angle, but well-lit in another. The two angles were shot at different locations weeks apart and weren't intended to be cut together.
In Albert's feet close-ups, his socks are different throughout. This discontinuity was deemed acceptable by the filmmakers as it takes place in a dream sequence.
An emergency vehicle siren is heard in the parking lot (to establish that it's a hospital). Real hospitals have a no-noise ordinance, and EMT drivers know not to blast a siren next to the hospital.
The Prep Room scene was filmed in a classroom at The Colorado Film School, and the acoustic ceiling tiles and vent are clearly not part of a sterile environment. The ceiling would be smooth in an actual hospital prep room.
A wheelchair next to Albert in the waiting room has no back support. It is actually used at the Colorado Film School for "poor man" dolly shots.
The tripod of an Arri location kit light stand can be seen in the lower left when Albert hops off the operating table.