Revealing mistake: When Otto holds Archie upside-down, out the window, the rigid outline of the support is quite visible under Archie's pants' material. (00:59:55)
Revealing mistake: When Archie enters the kitchen to talk with his daughter we can see Wendy reflected in the door glass moving in to position waiting to come in to the picture. (00:04:35)
Revealing mistake: During the trial, George calls Wanda a b*tch and runs towards her, jumping on the tables. The actor is replaced by a very obvious stuntman: younger, with a fuller moustache, and with longer and darker hair.
Revealing mistake: When Otto is shooting at the security camera we can see on the security screen that he isn't pointing directly at the camera, but to the side of the camera. (00:07:10)
Revealing mistake: When Otto is firing at Ken, while Ken is driving the steam roller, you can see the explosive pack on the steel post before the bullet hits it. (01:38:05)
Revealing mistake: Towards the end when Archie is driving Wanda to the flat in his car, during the shot when she asks him to "say something in Italian" you can see John Cleese is trying desperately hard to keep a straight face (and not altogether succeeding).
Answer: John Cleese was reciting the poem "Molitva" by Mikhail Lermontov. He learned and memorized it phonetically and has admitted that he had no idea what the words actually meant.
Angela Brown