The Crop Ate the Clock
optimal
The test clip failed in the obvious places first. The letter would not keep a shape. The closing hand lost its fingers. After the opening line there were more than three seconds of nothing. Those frames get regenerated. That is a diagnosis.
The clock was the quieter lie. Shot three crops the source before it enlarges it. The crop throws the clock out of the picture. The checker still looks at a fixed rectangle and reports the clock stable. A script can also certify a complete narration that never exported.
Concat and audio later checked out: 498 frames, 20.75 seconds. An unrendered draft sits at 18.75 with the later timestamps. The letter and the hand still have to be drawn again.