The 'Scouts' motto is 'Be prepared'. Same applies to AV!! The best you can do is try be as prepared as possible, as external & special events (kids holiday programs, conferences, youth evangelistic events) can be challenging and stressful.
You are going to want to bring your own sound mixer.
Create a cable count list
and add extra. For some reason people forget their cables. (But don't be excessive)
Have some trays to organise AV table desk
Bring more laptops. Honestly, having laptops fail is nothing new :(
Transport to venue: Usually fits in bands' cars. Approx 3+. Transport from venue: If someone leaves early, grab help from extra drivers
Flickering projectors due to bad HDMI connectors or weak signals do happen.
Pro move is to use a travel router