Already inside the mistake
The episode opens with Dennis and Dee hiding in a closet. Their artifact-recovery plan has become an intrusion into an occupied home.
Supporting source ↗CASE FILE · S07 E09

The gang sneak into a residence to "extract" an "artifact," only to discover that someone is home. Uh-oh.
THE SHORT VERSION · SPOILERS AHEAD
The episode opens with Dennis and Dee hiding in a closet. Their artifact-recovery plan has become an intrusion into an occupied home.
Supporting source ↗Mac and Charlie wait outside with a walkie-talkie. Inside, Frank searches luggage and handles a whip while the others try to leave.
Supporting source ↗The intruders build increasingly wild theories around travel preparations and Jay Leno tickets. The household is actually facing a relationship crisis.
Supporting source ↗The group finally walks out through the front door. Mac’s late diversion ends with the sought-after vase breaking.
Supporting source ↗THE EVIDENCE
Charlie raises binoculars while sitting in the van.Source ↗
Dee reads a slip of paper during the bedroom search.Source ↗
Dennis hides beside Frank and Dee in the crowded closet.Source ↗
Frank conceals himself among stuffed animals while holding his whip.Source ↗
Charlie looks through binoculars from his seat in the van.Source ↗
Frank examines the talking bear while searching the luggage.Source ↗
The white van is parked across from the house.Source ↗
Dee finds Jay Leno tickets among the travel papers.Source ↗
The white and blue vase stands on a table between the intruders.Source ↗
Frank speaks into a handheld radio in the bedroom.Source ↗
Mac eats from a bag while Charlie sits beside him.Source ↗
The group finally reaches the large vase near the front door.Source ↗
Mac arrives with his unnecessary Swedish-plumber diversion.Source ↗
The gang traces its artifact scheme to watching Indiana Jones.Source ↗
Tags document researched occurrences, not every appearance. Read the research notes and attribution.