The vat of liquid Jim identified as sulfuric acid was fuming and caused Willy to cough. In fact sulfuric acid looks like water and does not release mist or release irritating vapors.
After Paris feigns passing out at the party in his hotel room, Jocaro rummages through Paris's wallet and examines two IDs - a police credential and a drivers license. Both IDs state "Ojos: Azul" which translates to "Eyes: Blue". But Paris (Leonard Nimoy) has brown eyes, not blue. The reference "Cabello: Pardo" (Hair: Brown) is, however, correct.
Lieutenant Jocaro's name in Spanish would be pronounced "ho-ca-ro." The "J" is pronounced like a hard, even raspy English "H".
There are some Spanish words misspelled: "Flores Fresca" instead of "Flores Frescas", "JÉFE" instead of "JEFE", "Commandante" instead of "Comandante", "San Raoul" instead of "San Raúl", "HMOS." instead of "HNOS."
The driver license is correctly written in Spanish, except the title "Licenza d'automobile", which is in Italian.
All through the fight with Barney, Luis Corba holds his knife in his right hand. Immediately after he falls out the window the camera shows him as, apparently, having stabbed himself with his left hand. Then when Barney gets down to check him, he has the knife in his right hand. The film had been reversed for the short first shot.
Barney (Greg Morris) attempts to escape from a jail cell by using an electric arc to burn off the back of the lock. In closeup it is obvious the "steel" frame of the cell is made of wood since the wood grain is clearly visible.
Having seen the level of security present in the so called "death cell" block when he was lead to his cell, it seems rather odd that Barney would attempt to break out of the jail.
It seems odd that the intelligent yet irredeemably evil and sadistic Corba, would potentially incriminate himself by retaining the valuables of the criminals he executed.
After Paris gets the phone call from Jim Phelps alerting him that Barney Collier is in trouble, he is dialing the out-of-frame phone to call Willy Armitage. The dialing sounds continue, even after Paris' hand comes back up into the frame.
When Paris goes into Jacaro's office, you can briefly see a black flag used for blocking part of the lights on the right side of the frame.
When Jim receives a phone call from Alma, telling him Barney has been arrested, you can briefly see the shadow from the boom mike on the back wall.