There was a gap in between the houses in Caradoc Street so they built a false front for the 1930s; put a load of rubble in the road to look as though it had been bombed for the 1940s; and then put up corrugated iron for the 1960s.
In the boxing scene at the fairground, the twins' are portrayed as young adults and that the fight between them transpires after Ronnie knocks out the prize fighter - this incident actually took place when they were both small boys. The ringmaster shouted to the crowd if anyone wanted to take on the show fighter and the young Ronnie Kray shouted that he'd fight him. Amid much laughter, the referee pointedly said he was a bit young - whereupon Reggie stepped up and challenged his brother. They fought gamely, and were both awarded half a crown for their efforts; this was also the bout that led to their later semi-professional careers as pugilists.
Reg Kray takes Frances into her parents' garden where a 'decorative' garden gnome can be seen between them. Garden gnomes of the early 1960s were cast in plaster and painted but this one is of moulded plastic, a method of manufacture that wasn't used for this purpose until later.
In the slow-motion sequences of the fairground boxing scene, the filming lights illuminating the scene can be seen flickering very prominently, due to beating between the mains frequency of the lights and the very high frame rate used to achieve the slow motion. They should have used DC-powered lights!
Rose: I was on the bus the other day. And some old toerag was boasting about all he'd suffered during the war. Stupid old... I tell you, they don't know. It was the women who had the war - the real war. The women were left at home in the shit, not sitting in some sparkling plane or gleaming tank. There's no glamour for us. They should have been with me when old Pauline Woolley went in to labour. D'you remember that, Violet?
Violet Kray: Who loves you, eh? That's right, Mummy loves you, you little monsters. Mummy loves you more than anything - more than all the cakes, more than all the jewellery, more than all the chocolate in the world.