Jason and Sam were headed to the car's location and thanks to their injuries, they were rather slow in doing so.
Allison trailed them, she could easily gun them down, which would have been the more logical solution but something told her to follow them.
She always relied on her guts, and she still had the element of surprise.
Sam, however, was already aware of her presence, Sam knew they were being followed as there was no way he would let down his guard in enemy territory but he knew he couldn't let Jason know they were being followed or tip off the lady that he knew they were being followed.
Sam smirked, this could work in his favour as he momentarily thought how he could kill two birds with one stone.
"Yo Sam, you there buddy?" Jason called out, he wasn't hostile towards Sam.
Jason knew from his gaming experience and media consumption that one needed someone like Sam on their team.