I've been looking at some references of rockets taking off. I came across the Apollo 14 Saturn V launch and noticed that when the rocket was taking off the smoke coming from around the rocket and from underneath twisted around the rocket. I find this very peculiar. Why does this happen?
The effect is very prominent at around 42:10.
The effect you are seeing is simply wind, not a twist.
The reason for the diagonal direction is that the smoke is moving horizontally while the rocket is moving upwards, like this:
How can I be so sure about this? Well, viewing the other side of the rocket is not necessary: If the smoke was indeed ejected sideways, it would continue in the same direction because of inertia, away from the rocket as it curves away. But in the video the smoke follows the curvature of the cylinder, and that can only be explained by the wind causing a lower pressure on the leeward side of the rocket:
We can also confirm this by watching a Saturn launch were the wind speeds were very low, like on the Apollo 8 mission:
