Gastornis bird chicks: When you drink water through your trunk, does it taste like boogers?
Ellie: Uh no... Well... Sometimes, Now let's move!
When Scrat removes the giant acorn in Scratlantis the city is immediately flooded. Everyone in the background is blown away by the sudden rush of water. However, both Scrat in the background and Scrat's host (slightly off-camera) in the foreground don't move and don't seem to be affected by extremely strong flow.
The knife that is given to Louis by the pirates is the exact same knife that Buck had in the previous film.