When Cindy Lou visits the Grinch's house for the first time, she raps at the door, yet the sound it makes is noticeably different.
The Grinch's parents ought to have taken him to hospital after seeing him bite off part of the plate of Santa-shaped biscuits.
Parents can be neglectful or in denial about their children's problems. In this film the Grinch's parents are depicted as neglectful. What they 'ought' to have done is open to debate, but the story depends on parents who make poor choices. Had they taken the Grinch to hospital at that point, it would have been a very different film.
Whilst in Whoville, the Grinch's eyes occasionally shift from yellow to white.
When the Grinch is sorting through the post, a parcel drops to the floor. In the following shot, the parcel has vanished.
After the Grinch had loaded his sledge, he switched off every Christmas light. But as he prepared to set off, the lights were all lit again and his sledge stalled. On his second attempt to depart, the lights went dark once more.
Near the end, as the Grinch admits to having stolen Christmas, the sheriff's nightcap is positioned in front of his shoulder in one shot but appears behind it in another.
When Martha May hands the engagement ring back to The Mayor, she extends the ring box towards him while he looks at her and the ring with his arms at his sides. In the subsequent shot, Martha May’s arms hang by her sides, whereas The Mayor is holding the ring box with both hands.
Because Jim Carrey disliked wearing contact lenses, several shots were altered during post-production. In a couple of instances his natural eye colour is visible (for example, at about 59 minutes).
The Christmas lights Martha May fires at her house from the cannon do not seem to be plugged into any external power source.
An establishing shot of The Grinch assembling the sledge unintentionally reveals the camera's shadow.
Although the film is classified PG, a PG-13 rating screen appears at the end of the film; this, however, occurs only on the original VHS and DVD releases.
While the Grinch is pilfering presents from the houses in Whoville, he takes Martha May's ring from her bedside table. Later she slides down the sack of stolen presents and returns the ring to the Mayor.
She slides off the sack because she was retrieving the ring from it.
Notably, in the Grinch's flashback, when May Who and the rest of his classmates — apart from Martha — burst into laughter at his plight, even their teacher, Miss Rue Who, is seen giggling along. In real life, if pupils were acting so spitefully towards a fellow student, the teacher would almost certainly reprimand them rather than join in.
However, this was likely deliberately included in the script to provide an additional reason for the Grinch's intense dislike of the Whos.
Young Augustus May Who taunts the Grinch, pointing out that he’s eight years old and even has a beard. In reality, boys do not usually begin to grow facial hair until at least thirteen.
While that is true for humans, neither the Grinch nor the Whos are human, so human biology is irrelevant to the film.
Additionally, the scene depicts bullying. Bullies are unkind, and Augustus is intentionally cruel to the Grinch by drawing attention to an unflattering difference; this contributes to the film’s characterisation.
When Cindy is propelled from the rubbish chute and lands in the snow, the surface gives a small bounce, revealing a crash mat beneath.
While Betty Lou Who is winding up a string of lights and telling her husband Lou "it's all for the cause", a bulb goes out. In the next shot the bulb is back on.
