These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Fridge Brilliance / "Funny Aneurysm" Moment: In the years since this film was released, the international real estate and housing market (Which all the characters constantly refer to as booming and overflowing with cash) has undergone a collapse the likes of which has not been seen in years, and was actually one of the instigating factors for the worst recession since the Great Depression of the 1920s and 1930s. It was not intentional, he did not see the collapse coming, but in the commentary Guy Ritchie explains that this collapse came about because of exactly what the characters in the film are doing. Not the violence and crime, but people buying low-cost properties and inflating their prices and re-selling them in a long chain from one to the next until the entire system ultimately collapses under its own weight.
Harsher in Hindsight: Lenny immediately suspects that Johnny faked his death (before the events of the film began) and questions Roman, his manager, if he personally saw the body. Specifically, he asks "Did you see him hanging from the ceiling with his cock in his hand, like a real Rockn Rolla?" Cue the news of how David Carradine really died...
Ho Yay: Uri's right-hand man Victor is extremely protective, does his dirty work, follows him around like a puppy and hates Stella's guts. And all Uri's ex-girlfriends. And phones Uri to interrupt him proposing to Stella. Then he presumably kills Stella.
That was because she had come into possession of the painting, as a gift from One-Two. Neither of them were aware of its value or its true owner. Uri assumed she was the one responsible for its theft, and gave Victor the order.