Hi, I was wondering if there are any reasons why an all cash offer in buying a home can fall through ? Will the sellers agent consult the next in line that bid for the house ?
I’ll give you $2 (all cash!) for the laptop you’re typing on. Deal? 
Typically (ex)Californian, all cash offer 
How do you know he/she is ex-Californian?
The all-cash offer might still come with some contingencies, such as selling buyer’s current home, demanding repairs by seller, etc. Or the buyer can still change his mind right before signing escrow. Not typical but still possible.
Typical scenario: No real proof of funds established. They submit all cash offers with some junk proof, when seller agent verifies it, they may not see full cash 100% but may be 75% or 80% with some behind the scene loans may be there.
Back in 2012, my friend offered, 2nd best offer, Dublin home 650k (LP $600k) with 80% loan while he was defeated by all cash offer with $675k. Seller tried to accept all cash offer initially.
Seller agent verified cash source, buyer needs to sell some overseas home to bring the money to USA which is a long shot.
After few days of verification, my friend offer was just accepted (without any negotiation) and got the home finally with 80% loan.