Did you get it right?
Two modern material details do not fit this old bowling-alley maintenance room.

The Answer
The correct answer is: the hook-and-loop tool-pouch closure and the adhesive anti-slip strip on the step.
Here is why
- The canvas tool pouch at lower left closes with a dark rectangular hook-and-loop patch.
- The metal step at lower right carries a bright textured pressure-sensitive anti-slip strip.
Why people miss it
Both items look useful in a maintenance room, so their modern materials seem natural until the period is considered.
What answer did you get before checking?