Avengers: Age
of Ultron

In Age of Ultron, we saw glimpses of Thor visiting the Water of Sight. But in the full-blown sequence, Thor revealed a major clue about the Mind Stone under Norn's possession.

Thor: Ragnarok 

A post-credit scene of Ragnarok had the Grandmaster boarding the Asgardian ship
Ark to reach Earth. It was deleted later, but
just imagine what would have happened
if it was not!

When Bruce Banner transforms into the Hulk while trying to kill himself, a giant ice structure collapses. Captain America was supposed to appear from that for a quick moment.

The
Incredible Hulk

Shang-Chi

Following the release of Shang-Chi, a deleted scene was shared on Marvel's social media handles. In it, an interesting connection
between the film and the first Iron Man
movie was made.

Thor

We were introduced to Sentient World Observation and Response Department (S.W.O.R.D) in WandaVision. But, in the
deleted ending of Thor in 2011, Dr. Erik
Selvig talked about the department.