Snooki already has henna tattoos on her arms at the end of the shift at the store. Next scene Snooki & Deena are getting the henna tattoos after work.
The girls handcuff Pauly & Mike to the wheelchairs they're sitting in before the "cakes" are brought out. At 18:36 in right as the "cakes" are brought out, neither of Pauly's hands are cuffed. They appear & disappear more than once.