Spencer (2021)

Continuity mistake: In the opening scenes while lost on her way to Sandringham, Diana drives a Porsche 911 with licence plate G580SGT. Later when she stops by the scarecrow the same car's plate has changed to J548LRP, it remains so for the rest of the movie. J548LRP was an actual plate used on a Mercedes SL500 that Princess Diana once owned.

Continuity mistake: Diana used wire cutters to deliberately cut her left upper arm, about 3" from her underarm. When she went to the mirror to wipe it, the cut looked bigger (not just from blood) and was about 2" lower on her arm. Afterwards, there was little to no sign of the cut. (01:16:37 - 01:20:52)

KeyZOid

Continuity mistake: Her high heels in the bathroom are sole to sole, near the leg of the stool. Then, one is right way up and one is on its side in a different spot.

Charles: The chicken laid the eggs, the fishermen caught the fish, the bees made the honey. They all made such an effort to bring you breakfast. Please do them the courtesy of not regurgitating it all into a lavatory bowl before the church bells even ring.

Diana: Will they kill me, do you think?

Princess Anne: "Half my weight's in jewelry, anyway." Do you remember when she said that?
Major Alistar Gregory: I wasn't here, but I heard about it.
Princess Anne: Is she here yet?
Major Alistar Gregory: Not yet, Ma'am, no.
Princess Anne: Then she's late. And he is early.
Major Alistar Gregory: And yet she is late.