When Urkel begins his live confession of his love for Laura, a balloon tied to a string can be seen behind him. It disappears between shots after Pat reminds him they're being filmed. The confetti also disappears from Urkel and Pat's shoulders at this point.
As Eddie is getting up to sing his song, two boom mics are visible. One disappeared quickly, while the other one hung around for a few seconds before being raised out of the shot.
When Oneisha gets up out of her chair after she chose Steve, and boom mic was visible above the three girls before being raised out of the shot.