The movie starts off during a dark night. usually dark nights symbolize mystery and uncertainty in movies. with this it helped build suspense because we don't know what's about to happen and we don't know what could be lurking in the shadows
This is a very suspenseful scene because right after getting chased by zombies, he falls and gets cut on some glass. The real suspense is when he sees dark figures approaching from within the shadows.
Our protagonist gets a flashback of who he saw dead in the back of his car, the scientist. This scene helped build suspense because he is carrying a gun and we the audience don't know what his true intentions are.
The cab driver remembers that the scientist wrote something in the back of his lottery ticket, we have no idea what could be written in the back of the lottery ticket so that builds some suspense.
In the final scene he finds out that the zombies ignored him and went outside only to see the zombies get killed by a helicopter. this is extremely suspenseful because the video ends there and we don't know if the protagonist lives, dies, or turns into a zombie.