Some Problems with the script.
Scrimping on 'Crisis Actors' is a false economy.
Footage of panicked extras running around getting shouted at by 'police' makes it real. The shouting is crucial - the audience empathizes with the actors so much that they think if they step out of line and question things, they'll get shouted at too - they wouldn't like that!
It helps a lot if there's at least one corpse.
Doesn't have to be a real one of course :) , but people are very respectful of death, and will bottle their incredulity if someone with a heart-rending backstory is cut off in her prime.
If you're going to lie, lie big!
Ok, it's not a tiddler, but really it could have been bigger.
Why not have lots of casualties (actors), not just three. Then, as per previous point, some of them could have 'snuffed it'. This would also have been more plausible, given the supposed lethality of this stuff.
Given the nature of the 'attack', it would have been plausible to have had all casualties whisked away to a 'special military hospital unit' somewhere, and then you avoid contamination of NHS staff (wouldn't have had to involve pesky NHS civilians, who don't always stick to the script)
Don't kill animals needlessly.
For god sake - what on earth where you thinking of!
While a dead human would have shut people up, a needlessly killed cat is going to have the nation of pet lovers up in arms and asking questions.
No Videos?
Wouldn't have been difficult to leak some grainy footage of someone feigning a fit and pissing their pants.
Where's the Hero of the story?
I know we have the police officer, but we're not sure what he actually did (again - where's the video?) Also why is a Detective Sergeant first on the scene, not a constable or PCSO - On a sleepy Sunday afternoon?
Might strike a better chord with the Audience if you had a 'member of the public' or ex-services chap leaping into the fray to help out.
If you only have a few main characters, they need to be A-listers.
BTW: You didn't really try - and fail - to kill off the Skripals did you? I'll assume not.
Yulia has already fluffed her lines in that phone call to her cousin, also logging onto Facebookski while in a coma? Very amateurish. Better give her a rest. Here's hoping Sergei - being a pro - will carry it off much better.
Also While BoJo clearly has talent - a brilliant obfuscator and ad-libber, think he might have been miscast here. Need someone who can stick to the script.
Ok to confuse a bit, but don't bewilder or take the piss.
Changing the official theory on the method of delivery of the poison once or twice would have been fine. But five times? or was it six? I've lost count.
No loose ends.
Hard to avoid a few, and normally if you follow the main points above, audience will get bored and move on before they notice, apart from the tin-foil hatters of course ;)
For instance, the hospital staff. That consultant who wrote to the times clearly didn't have his story straight.
Also , having to disallow VISA for cousin Vicky looks unkind.
General problems of the scenario employed.
While the idea of using 'Novichok' agent might at first seems perfect for pointing a finger of suspicion at the Russkies. It does introduce a number of problems.
For instance, the necessary testing of samples at Porton Down and then OPCW takes weeks, and drags the story out, giving the audience more time to think about it - not a good thing! especially given the far from conclusive result.
The problem of definitively pinning the Novichok to Russia was foreseeable, and some corroborating piece of evidence needed to be offered.
Given the need for this extra piece of 'Russkie smoking gun' evidence, the question arises, "Did the whole Novichok scenario cause more problems than it was worth?"
Taken together it all makes me think this hasn't been thought through as much as it should have been.