When Jack lets slip about Will's affair with Steven to Grace, he throws a blue tassel to the floor, and bends over so Grace can kiss his butt. But when he stands up he puts a purple tassel back on the table.
The amount of frothy foam on top of the protein shake.
When Grace gets out all the videos which hint Will's 'secret', she puts the bag on the table, but in the next shot it's in her hand. Between these same shots a sticker also appears on one of the video cases.