In a scuffle with Michael Caine the hatband of Liam Dunn's fedora is torn and left hanging from the brim. In a later shipboard scene, Dunn is holding the same fedora, and the hatband is back in place.
Near the end, when Tucker is climbing the rope on the cruise ship, the long shots show knots in the rope. No knots in the rope on the close-ups.
When Tucker and Billy Pate are leaving the Pendergast mansion, there was another car blocking the driveway entrance. Tucker hits that car and pushes it aside, clearing their escape, the car that was blocking the drive then drives into the estate and around the turnaround, then out of the estate through the gate to start their pursuit of Tucker. BUT the very next scene has them hot on Tucker's tail! Just what was Tucker doing while the second car was driving into the Pendergast estate, around the turnaround, then out the gates to the highway? Waiting so that the viewer could have the prerequisite car chase sequence? (a necessity for PI films ever since Bullit!)
Tucker is finally able to get off of the lifeboat and back onto the ship. Just as he does so, he hears a splash, and he looks over the side of the ship, only to see the hanging ropes that once held the lifeboat, and the sea, BUT no lifeboat. As he looked immediately after hearing the splash, the lifeboat would have still been where it had splashed into the water. The speed of the ship (20-30 knots) would NOT have been so fast as to get away from the lifeboat (leave it behind) and so get it out of the view of Tucker that quickly. As he did look immediately, it would have sill been there, and therefore he WOULD have seen it.
When Tucker fights Rosie and Sid on the lifeboat, it is on the port side of the ship (left side). BUT at the end of the movie, the ship is seen from a distance (going from the left side of the screen to the right side of the screen) with Sid and Rosie (in the lifeboat) closer to the viewer's point of view. That now places them on the starboard side (right side) of the ship.
While Tucker is suspended on a rope holding the lifeboat, he swings back and forth in an effort to swing himself back onto the deck of the ship. He successfully does so, but never lifts his legs to clear the railing of the deck of the ship. Therefore, he ether goes right through the railing (like the terminator in Terminator II going through the bars in the psych ward), or the set had the railing removed for the shooting of the scene.
While being pursued on a bumper to bumper LA freeway, Tucker manipulates his way from being in front of Rosie to behind Rosie. He then rear-ends Rosie, causing Rosie to rear-end a car transporter truck. The back most car on the upper deck then rolls off of the transport and down onto Rosie's car (thereby disabling Rosie's car and allowing Tucker to make good his escape). BUT cars on transporters are always secured (usually by chaining them to the frame work of the transporter). Otherwise, accidents would be frequent and transporter manufacturers and the owners of transporters would get sued right out of business, and thereby destroy those industries). But they do still exist, so...
Tucker chases Billy through the ship, through the dinning area, and into the kitchen. There (off screen) he overcomes Billy and brings him out of the kitchen, into the dinning area, and straight to the table where the Pendergasts are seated. When he comes out of the kitchen, he does NOT look around for the Pendergasts, he goes straight to them just as if he had been told by the director where they were before shooting the scene (either that or the character Tucker, unrevealed to the viewer, was a clairvoyant).
In the dinning area, as Tucker is revealing everything that has happened and why, Ellen (who is opposite of Tucker) gets up (off camera, but in full view of Tucker) and sneaks around the table, and successfully grabs the suitcase with the money (and runs away). And she does this in full view of Tucker! So the only reason that this maneuver takes Tucker by surprise must have been because that was what was in the script.
Tucker is fighting Rosie and Sid, and end up in the lifeboat. Ellen goes to the red handle and lowers the lifeboat. But how did she know that that red handle would lower the lifeboat? Unless someone had the knowledge of a crew member, the vast majority of passengers would not have even the foggiest notion of how to lower a lifeboat. But then, there is always the director to impart such knowledge.
The cruise liner at the end of the film looks far too modern for 1947. It is the MS Starward, built in 1968, and still in service today as the MV Orient Queen.
The road stripes during the car chase are wrong for the period. The road has a double yellow centerline and yellow road reflectors. Yellow centerlines were not adopted in the USA until 1971. The bridge railings are also too modern for the period.
When Ellen and the torpedoes are running away from Jaster's office, they pass under a theatre sign with the names Celeste Holm and Mark Stevens. Holm and Stevens appeared in the film The Snake Pit (1948) which was released in 1948. This film's title card reads "Los Angeles 1947".
A scene is filmed with two autos playing tag on the L.A. freeway, which was not constructed until the 1950s.
Tucker NEVER does check the suitcase to make sure the one he has does have the money. And he does NOT do so even after the first case after the first suitcase that he thought had the money was revealed NOT to have the money. One would have thought that after that mistake (when he was so sure) he would double check to make sure his now second choice was correct.