Give her a real place in the arrangement
Movie night chaos usually starts because the cat was never actually planned for. The family spreads across the sofa, the snacks take the side tables, someone dims the lights — and the cat discovers her usual spot occupied, interesting food at nose height, and a dark room full of sudden noise. Involving her starts with a seat that is hers on purpose: one end of the sofa or the armchair beside it, layered with the blanket she already sleeps on, close enough to be stroked but with a clear route out along the back of the sofa or to the floor.
Some cats prefer observation to contact and will enjoy the evening most from a raised perch behind the sofa, watching both the screen's movement and the family. That counts as involved. The aim is a cat choosing to stay in the room, not a cat placed on a lap and managed for two hours.
Spend her energy before the opening credits
A cat who has hunted, caught, and eaten in the last hour is a cat ready to wash and doze through a film; a cat who slept all day and missed her play is a live wire looking for a job, and your ankles, curtains, and snack bowls are the obvious vacancies. Run her best interactive play session twenty minutes or so before the film, finish with her evening meal or a small portion of it, and let that natural full-and-tired sequence carry her into the first half of the movie.
Settle the room during this wind-down rather than after she is already asleep in her spot. Cushions arranged, drinks poured, remotes found, and the inevitable mid-film snack run minimised, because every human getting up and down, opening doors, and switching lights on is a small restart to a resting cat's evening.
Make the snacks, sounds, and screen cat-proof
Human movie food is the main source of both chaos and genuine risk. Bowls on laps get investigated, and foods that are harmless to people can be unkind or unsafe for cats, so keep snacks on a surface she cannot reach, use lids or covers during pauses, and give her a small approved treat of her own at the start so the evening includes her without sharing the buffet. Cables for chargers and headphones trailing across the sofa are dangling toys to a wide-awake cat, so route them behind cushions before the lights go down.
Sound deserves the same thought. Sudden loud effects are the part of a film a cat experiences physically, so keep the volume a notch below your maximum, especially for action films, and consider a calmer first few movie nights while she learns the routine. A cat who leaves during explosions and returns for the quiet scenes is managing herself sensibly; leave the door ajar so her exits and returns never require a performance.
Let leaving be allowed, and keep the ritual repeatable
The rule that protects the whole idea is that attendance is voluntary. Never shut her in for the duration, carry her back when she leaves, or let children fetch her for a cuddle scene she did not audition for. A cat free to go is paradoxically the cat most likely to stay, because the room carries no trap associations, and over a few weeks many cats build movie night into their own routine, arriving when they hear the familiar setup sounds.
Keep the format steady while she learns it: same evening slot, same blanket in the same seat, same play-and-feed sequence beforehand. Note what works — the films whose noise sent her off, the seat she actually chose, whether she prefers the perch to the sofa — and adjust one thing at a time. Recording her settled movie-night setup in KinsLe's Family Sharing means whoever hosts the evening, parent, teenager, or grandparent, lays out her place exactly the way she likes it.