Sabrina announces that Kris has walked out of Karazna's house before Kris can be seen.
After Mr. Karazna hops in the plane, there is a shot of him jiggling the yoke back and forth as though he is flying the plane, even though the next shot shows the engine hasn't even been started.
After Jill tells Karazna about his son, he looks over his shoulder at the boy's portrait. The close-up of the painting is flipped horizontally.
Kris pulls into the parking lot of the Mexican food place. She parks the car and the back passenger tire is clearly way over the white line. When she gets out and walks to the back of the car, the tire is on the white line.
After Kris is kidnapped, Charlie says he'll tell Jill, who is in Montreal. Montreal is over 8 hours away by commercial jet but Jill arrives in small, twin engine piston airplane. An airplane of that size wouldn't have the range to make the trip non-stop, and would have taken about 9-10 hours, yet it is still daylight.