If you get the acorn in the pillar paths section in world 2, which moves randomly as you move, the run's over, because the cutscene of Mario grabbing the acorn is long enough to cancel any time save before/after it.

Does anyone know a consistent way of avoiding it.

Man I love RNG so much.

Yea for an optimal time the Acorn on the pillar on W2 is a run killer (5-6 secs time loss).