The note read by Irene detailing the plan has different line wrap and layout than that prepared and displayed earlier that day in the film.
The damage to Lester's right front fender comes and goes during the final chase scene.
The train leaving New York en route to Chicago is pulled by a streamlined steam locomotive of the Southern Pacific Railroad that was used in California. Later that evening, another scene at night in Pennsylvania shows a different type of locomotive pulling the train. The Southern Pacific locomotive is seen again pulling the train the next morning. Whilst approaching Chicago, Lester asks the conductor if he can get a ticket for the next train from Chicago to San Francisco. The conductor says he will check on getting a ticket on the California Zephyr. However, the two men are standing in the vestibule of car CZ-10, which IS a car that was the observation dome car on all California Zephyr consists. Whilst having breakfast on the Zephyr in the mountains of Colorado, Myra comments how much she enjoyed their tour of Chicago earlier that day, but, travel through Colorado would actually occur on the NEXT day, following an overnight journey from Chicago to Denver.
The SoundScriber soft vinyl recording disc that Myra drops breaks like a hard shellac 78 rpm phonograph record, which could break into distinct pieces when uneven pressure was applied.
When Myra sits at her desk to check her time schedule, the clock throws a shadow of the pendulum sweeping back and forth across her face. The Shadow moves faster than the actual pendulum on the clock.
After Lester puts down Irene's telephone, he calls out her name three times, but on the second, his lips don't move at all.
When Junior brings Irene to her apartment and refuses to leave, she tries twice to close the door. Each time, a stagehand's hand can be seen reaching for the knob from out in the hall, a common practice on stage sets if a door doesn't latch properly or stay closed.
Myra could not know for certain that Lester would decline to follow her suggestion to carry on to the party. Had he gone there Irene would have inevitably discussed with him the fake assignation note, apparently from him, but planted by Myra. At that point they would both know that Myra was aware of their affair and was playing them.