The Disadvantages of Jai's Story

Jai says it was Adnan that dropped him off back home after they dumped the shovels in the parking lot of the mall. Jai never mentioned calling Jen or Jen coming over to pick him up from the parking lot or Jen taking him to his girlfriend's home ever in any of his testimonies. I don't for the life of me understand the discrepancies in Jai's story. If he can lie about this and so many other small details what else can he lie about? Maybe I'm wrong but I was.