For small orders, the items will be visible on the right side of the scan & pack interface. You can cue any order in the Scan and Pack section to view what has been scanned. For larger orders, the options below are better suited.

Exporting a scanning record for one or more orders

One option is to export the order to a CSV file. This is ideal for very large orders or when you would like to see the scanned items for multiple orders. Before exporting you can check that the standard order export option is selected. This can be done in Settings > System Settings > General. You'll want "Standard Order Export" selected in the dropdown under Misc. Settings.

In the orders section you can now select one or more orders and use the "Export Items" option in the edit dropdown. In the CSV that is exported you'll find columns for the Scanned and Unscanned qty of each of the items in the order.

Viewing scanned items in the Activity Log

You can view a list of all of the orders activity, including each of the items that have been scanned by clicking on the order number where it appears in the center of the Scan and Pack interface:

...and then clicking on the Activity/Exceptions tab:

The activity list can be searched using Ctrl-f (Command F on Mac). This makes it easy to find a specific SKU.

It's also possible to Select All or Part of the Activity log and print it using ctrl-p (command p on mac). This same method can be used to save a pdf of the items if you print to pdf.

Save as Text from GPX

The GPX app has the option to save the activity log as text on the Activity and Exceptions tab. This makes it easy to get a log of the scanned items.