The Great Guelph Museums Artefact Heist!

It seems the puppets in the Families Gallery have stolen some of our artefacts, and replaced them with forgeries!
Can you help us catch them in the act?
Here’s how we think the heist happened…
10:25 PM, Wednesday, March 18: Video camera footage shows a meeting of the puppets.
Our museum experts suspect that this is when their ringleader, Logan the Lamb, convinced the other puppets to help him steal some of Guelph Museums’ artefacts, and replace them with forged copies.
Here’s how you can help:
These puppets are clever, but they can be a bit careless. Each forgery contains three mistakes, and the footprint of one puppet. If you can find them all, we can prove what happened!
For reference, we’ve put a photo of each original artefact next to the forged copy. The originals have a “Guelph Museums Archival Material” label, and the forgeries are all in brown frames.
Ready to crack this case?