Daphne speaks to Frasier from the doorway of her room. From his POV the edge of the door is by her cheek. From her POV, the edge of the door is in front of her face.
Martin notes that the 'chunky' candy in the vending machine is $.85 and after he gets change for his $10 bill, he puts 4 coins in the machine, but twice due to different camera angles.
When Niles is being wheeled into surgery, it shows the scene of Daphne kissing him just a minute before from the view of the hallway. Frasier, Martin, and Roz should be behind Daphne, since they were in the room at the time, but in the memory, Daphne and Niles are alone.
When the doctor says Nile's blood pressure is 100/60, Frasier says it could be better. Actually, 100/60 is the best possible blood pressure one can have, opposed to the standard 120/80 which is considered normal.
Niles looks far too good to be a post-CABG patient. Patients that have had by-pass surgery don't go back to a regular hospital room. They go to an ICU. And they are rarely taken off the ventilator and are not extubated
until at least a few hours have passed, to allow for the anesthesia to wear off. By-pass patients usually have at least one chest tube, a large bore IV in their shoulder. Many times the patient would be on two or three different medication being controlled by IV pumps. All of this and sometimes more. Niles didn't look like he'd been through anything.
While the doctor is talking with Martin about his wife's prognosis, as part of a flashback. He is using two x-rays to explain what is going on. There's a lateral view (that is a view from the side). And there's AP view, anterior & posterior (front to back). The AP view is backwards. The heart is on the right. This is something a doctor would correct the moment he looked at the X-ray, because it something that would jump right out at a medical professional.
There is a condition called "dextrocardia" where the heart is found on the right side of the chest. It's a congenital condition that is extremely rare. Most people with that condition live normal lives, not knowing they even have the condition until they happen to get an x-ray, or a thorough exam.
As Niles lies in his hospital bed, the first card he reads is from his mother-in-law, which goes, in its entirety: "Dear Niles! I know we haven't always gotten along."
But his mother-in-law is English. She'd have written "got along".