Hi NuName,
Pending the routing of your trip and the type of aircraft you might require a US Waiver. This normally requires about 5-7 open working days to be processed. All pax require visa unless the operator is part of the Visa Waiver Programme. Customs in Las Vegas is not that flexible with regards to late arrivals, make sure you call them day(s) in advance. Last but not least, E-APIS.
Any questions, just ask.
Best regards,
GLJ Dispatch