Summary

The Escrow contract could use the minimal Proxy Standard (EIP-1167) to save gas on deployment.

Vulnerability Details

The Escrow contract is meant to be deployed multiple times by different buyers. Moreover there is a Factory contract for doing this. Therefore it would be a reasonable idea to use the Minimal Proxy Standard (EIP-1167), which uses a single implementation Contract instance of the Escrow contract and deploys only a minimal proxy for each individual escrow instance.
This would save gas on every new deployment.

Impact

Gas savings on every deployment of a new Escrow instance

Tools Used

Manual Review

Recommendations

Use Minimal Proxy Standard (EIP-1167) for the Escrow Contract.