When processing a return there is a field you set as your return reference id.
You can use this return reference id to bring up a list of SKU's returned with this id set.
This can be done in two ways
From the Inventory home page click Return to Supplier (you can also access this option from the plus icon)
Locate the Return Ref Id field and use the drop down to select the Ref ID you are looking for.
This will automatically load list all SKU's you returned using this Return Ref ID
You can even select this info and copy it to paste it into another document if needed.
Another way to get this info is through a smart set.
From the BusinessMind home page click on Inventory
From the Inventory Home Page locate the View Sku's area
Choose the option to make a New Smart Set Query
Set up your search criteria for Event Ref ID and Search for the Return Ref ID in question as per the screen shot below