When Penny, Amy, and Bernadette are dipping their hands in wax, and while Bernadette is talking, the camera switches from Bernadette to Penny and then back to Bernadette, and the wax on Bernadette's hands go from completely hardened back to freshly dipped. The camera switches to a wide angle of both women, and the wax is hard and peeling off her hands again.
It makes no sense for Raj to bring Harold to his date with deaf Emily just to translate sign language. Being a tech nerd, he could just use his phone or a tablet to write things down, and have privacy.