These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Jeff: There's nobody, quite like you, Muffy, nobody does the things you do... Where would we be, if we didn't have you? Our days would be empty, the nighttime too, without you there'd be no sun in Sunday, all of our rainbows would be pale and gray.
Ear Worm: Not only the magic spell (see, now you remember this show) but also Sam's Leitmotif ("Singin' Yo-he-ho, sail across the ocean blue!"), the Blue Cow song, the theme song, etc.
Family-Unfriendly Aesop: The Christmas special. Jeff is sorry but resigned to the fact that thanks to his not being able to leave the store, he will have to spend Christmas alone while the others are with their families. The others then decide they care so much about Jeff that they will celebrate Christmas with him at the store. A very nice gesture, but is it fair to their actual families, who were looking forward to seeing them on the holiday, whereas they are with Jeff day in, day out?
Fridge Logic: So how can Jeff function on the roof if the magic hat specifically works only within the store?
In the opening credits, Muffy takes off Jeff's hat in order to make a scene transition. Why would she use this type of method, knowing that taking off his hat would turn him back into a mannequin?
In the episode "A Visit to the Opera", Jodie and Sam have to hold down two levers on a special machine belonging to Waldo and not let go of them so that Jeff can go outside. This would be too much of a great risk considering they would be the only two in the store. And what if an emergency occurred (burglary, fire, etc.)? Or what if they needed the restroom?
Somewhat related: Jeff is occasionally frustrated by the fact that he is the only object in the store that is in any way self-aware. (But what about TXL?)
Do any of the day shift people have any idea what goes on at night?