Did you get it right?
The science fair looks like the 1950s, but two display details belong to a much later era.

The Answer
The correct answer is: The clear plastic zip bag and the QR-style badge on a display board..
Here is why
- Look for the clear zip bag holding a sample.
- Find the square QR-style badge on one display board.
- Those are the two modern intrusions.
Why people miss it
The colorful exhibits and student activity create a lot of visual noise around the tiny modern clues.
What answer did you get before checking?