When they find the C4 Carrie and Al panic, telling everyone to turn off their phones and radios. This is hugely over dramatic and unnecessary.
Unless one of the cops accidentally connected the battery of their phone or radio directly to the block of C4 absolutely nothing would happen.
If dropping, shooting, burning or microwaving C4 can't set it off, then a phone or radio won't.
During the chase scene, Carrie's shoes switch between heeled boots and flat sneakers. During the 36 Minute 12 Seconds (gets out of the car to apprehend the bomber) - 39 Minute 13 Seconds (Handcuffed Bomber)