>>19824319at 0:21 the top of the guardrail becomes visible and does not move in relation to its surroundings.
In other words the most distant object already is fully visible right after the camera moves up.
Below the guardrail is an obvious distorted mirage that gradually disappears; this means the area the street fills is visible right from the beginning, not hidden by any sort of curvature, but the mirage reflection, which is gradually "replaced" by the actual image.
