La Brea TV show on NBC

I was excited to catch the premier of the La Brea TV show TV Ratings: ‘La Brea’ Drags in 6.2 Million Viewers to Its Debut on NBC (yahoo.com)
 A half-mile wide sink hole opens in Los Angeles, centered at the Page Museum of the La Brea Tar Pits. People, cars and buildings fall past 20,000-feet of strata and through an electric transition in the sky of La Brea. The four-miles of rock has miraculously disappeared and everything makes a soft landing on the surface.
It turns out that La Brea has the same topography as Los Angeles and an ecosystem resembling that of 14,000 years ago. The California megafauna include mammoth, mastodon, giant and Shasta ground sloths, camels, horses, bison, giant beaver, glyptodonts (imagine an armadillo the size of a VW Beetle), and predators. Dire wolves are well depicted as is the smilodon saber tooth cat. The California lion, giant jaguar, giant short-face bear (weighing up to a ton), grizzly bear, black bear may all make an appearance in good time California Megafauna Map | Roman Jaster . We are shown other humans live in La Brea. Whether La Brea is an artifact of ancient Earth or an alternate version where the megafauna has not died out is yet to be revealed in this weekly serial.
Large teratorn scavenger birds fly up through the sink hole revealing to the surface that living things exist down below and can survive rising through the transition. On the other hand, an attempt to fly a military drone to the bottom fails at the transition when electronic communications are disrupted. It may be the sink hole is too narrow for fixed wing aircraft to navigate and there is no guarantee of a clear landing strip. It is not clear to me whether a helicopter could make the journey with a human pilot. An older model, such as the Queen Bee, with direct controls and analog instruments might better survive the electric transition.
Perhaps a hot air balloon could make a two-way trip. Ideally a blimp or dirigible with diesel engines might make the journey with minimal disruption.
Rescuers should arm themselves as they would for Africa to say the least. Vehicle mounted .50 Browning machine guns would not be excessive. If there is a shortage of elephant rifles, auto-loading 12-gauge shotguns loaded with slugs and buckshot would have to make do. What sidearms would you suggest?