After Ophelia leaves Gomez and picks up Cousin Itt, the stem of the daisy in his lapel progresses out to the side, clearly visible. It is hidden again when Morticia tells the preacher what her name is.
When Morticia goes to "capture the light" from the thunder storm before the canvas rips you can see her shadow coming through the canvas. This suggests it's a very thin canvas (or even paper) to make it easy to rip.
Around 19:20, Morticia plays the role of her sister and sings a few notes on the lyre. Uncle Fester then says, "Ophelia, your voice needs tuning" but the movement of his mouth says "You're out of tune."