A Flea in Her Ear, Old Vic, LondonGet Santa! Royal Court Downstairs, LondonAntony and Cleopatra, Roundhouse, London

With one actor as master and servant, the pace is fast and frenetic in a French farce that suits the panto season – bar the odd questionable gag

In Georges Feydeau's vintage farce A Flea in Her Ear, turn-of-the-century Paris is in a spin.

At the disreputable Coq d'Or hotel, where philanderers and innocents have converged, the supposed adulteries and mistaken identities are multiplying like crazy. This gilded hub of belle époque decadence becomes a blur of slamming doors, shrieks and ricocheting bullets. Red-faced ladies dart across landings and moustachioed gents hurtle up the spiral staircase, fleeing scandalised cuckolds.

Richard Eyre's production (using John Mortimer's translation) was a triumph of tightly choreographed chaos on press night, though the pint-sized star Tom Hollander still bore a visible scar from a preview. One door swung the wrong way last week, smacking him in the face.

Hollander is terrifically funny, switching between roles at lightning speed. He doubles as the punctilious bourgeois husband, Monsieur Chandebise – lips pursed in a tight little "o" – and the reeling drunk hotel porter, Poche, who juts his bottom out for spankings, beaming like a simpleton. Think Buttons gone to seed. Chandebise's wide-eyed wife (Lisa Dillon) – almost caught in flagrante with her louche admirer (Jonathan Cake) – thinks that Poche, being a dead ringer, is her spouse gone doolally. She bundles him off to lie down at home.

This leads to a second round of near-surreal confusions: Hollander yelps that he's just seen himself asleep in his bed and takes a flying leap through a window. John Marquez is also splendid as a flamboyantly caricatured, pistol-popping Spaniard, vociferating as if he's gargling phlegm.

That said, Rob Howell's Coq d'Or set is peculiarly scrappy. The ratcheting mechanics of farce, though fast paced, feel predictable. Moreover, some of Feydeau's minor characters fail to amuse, not least Chandebise's nephew with his cleft-palette speech impediment. Even those unbothered by political correctness might wonder if a near-rape scene doesn't – these days – require a shift in tone. Still, cavils aside, a buoyant romp, considerably better than your average panto.

The Royal Court, meanwhile, presents its first ever family Yuletide show, Get Santa!. Though best known for his darkly twisted early plays, Anthony Neilson has written and directed this in silly-season mode – his jovial flip side. Holly, his heroine, is an entertainingly stroppy little girl: an impressively assured stage debut by Imogen Doel. She hates Christmas, isn't interested in stupid presents. She has asked Santa, every year, to bring her long-lost dad back, but her one-item wish list has been ignored.

This Christmas Eve, she's determined to trap the snowy-bearded, crimson-suited cad, dolloping glue on the mantelpiece and strewing noisy crisps near the fireplace, so he has no chance of tiptoeing undetected. Instead, Holly catches Bumblehole, the flailing son of Santa, who has a shaky grasp of magic spells. Her toy bear is brought to life for 24 hours (courtesy of a puppeteer). But then Teddy, villainously claiming to be Holly's dad trapped in a fluffy body, schemes to prolong Christmas Day interminably.

The cast's tongue-in-cheek musical numbers are droll – deadpan carolling about festive banalities – and Holly's stepdad is nicely off the wall. Did I mention her mum has married a St Bernard – a tubby bloke (Robert Stocks) in a brown woolly with a wagging tail, who keeps ruffing that he's chuffed, chuffed, chuffed?

Miriam Buether's set design looks fabulous as well: psychedelic retro chic, with fuchsia-pink wallpaper, yellow armchairs and Tom Godwin's ectomorphic Bumblehole dancing around like a quiffed elf in emerald green. None of that, however, conceals that Neilson's plot becomes a sprawling muddle when 25 December starts repeating over and over.

The only full-blown tragedy last week was Antony and Cleopatra and, alas, what really makes your eyes water is that this RSC transfer is so gobsmackingly bad. That this clueless, pig's ear of a production is the work of Michael Boyd – the company's artistic director – beggars belief. For sure, the RSC season's pop-up auditorium, specially constructed in the Roundhouse, is pleasing, the audience snugly encircling a simple thrust stage. However, this show is bare boards and no passion. One can only sympathise with Darrell d'Silva's stolid Mark Antony when he impales himself on his sword. Kathryn Hunter's Cleopatra hasn't only made him lose the Battle of Actium, she's absolutely massacring Shakespeare's poetry.

One struggles to see what has drawn him to her in the first place. Could it be her awful turquoise and chocolate frocks? Or is it her physical habit of waggling to and fro, like a string puppet caught in gale?

To be fair, Hunter's Cleo has a vein of spry playfulness, paired with neurotic insecurity, which might inspire protectiveness. Yet her mercurial mood swings, sans comic timing, are devoid of charm. She races through half her lines, as if on fast-forward, and pauses at the wrong points in others. By Act V, she's reducing Cleopatra's bereaved, beautiful, closing speeches to near-gibberish – a travesty! The man sitting in front of me was clearly suffering too, slapping his palm repeatedly into his forehead, then flinging his arms heavenwards.

'A Flea in Her Ear' (0844 871 7628) to 5 Mar; 'Get Santa!' (020-7565 5000) to 15 Jan; 'Antony and Cleopatra' (0844 482 8008) to 30 Dec

Next Week:

Kate Bassett is outward bound with Swallows and Amazons, staged by Tom Morris and Tony Sedgwick, both previously acclaimed for War Horse