When Abby calls Colin the first time and Mike hangs up on him there is a dial tone on Colin's line but the cordless Mike is holding is not disconnected yet. There shouldn't be a dial tone beacause his phone is still connected.
When Mike and Abby take off in the hot air balloon, the background shot shows the balloon high in the air (at least above the height of other balloons). However, the next shot of Mike trying to get off shows the balloon nowhere near that far off the ground.
When Mike helps Abby talk to Colin on the phone, a green light appears when Colin is on hold. As the scene switches back and forth, the light turns red at one point, then back to green. Colin was on hold the entire time.
The balloon festival is given to be in or near Sacramento. Sacramento law prohibits hot air balloons from flying around the city due to a fire hazard. It is one of a few cities in the world to have this law. The festival actually takes place in Temecula, over 450 miles to the south of Sacramento.