best comparisons ranked in order (per my opinion)...
1. Home - Original film, Opened in March, 7pm shows $.65M
though an argument can be made that spring break was starting in areas, it wasn't throughout the entire country (like a Thanksgiving holiday). we're starting to get enough data from midnights to have some valuable comparisons.
2. Lego Movie - Original film (but nostalgic), Opened in Feb, 10pm shows $.4M
this would almost be a better comparison for Zoo than Home if the shows had opened at 7pm, and the nostalgia factor wasn't in play. that said, the $400k midnight number resulted in a nearly $70M opening weekend.
3. Big Hero 6 - Original film, Targeted boys/young men, Same studio, Opened in fall but school was in session, $1.4M
a pretty decent comparison, but I think the $1.4M signifies that more teens and young adult males went to this film. for example, though I didn't see it Thursday opening night I did go see this with a buddy of mine (and Wreck-It). I would not seek out my buddies to go see Zootopia (like Hero and Wreck-It). I feel that alone inflated the $1.4M number.
don't think these are great comparisons...
4. Good Dinosaur - Opened on Wed over Thanksgiving holiday... holiday break really skews numbers
5. Minions - Built in fanbase, Opened during summer break... summer break and sequelitis present fan frontload
6. Inside Out - Original film, Pixar fanbase, Excellent reviews, Opened during summer break... summer break is enough to disqualify this as a great midnight comparison
7. Frozen - Original film, Targeted girls, Opened on Wed over Thanksgiving holiday... targeted for girls and holiday break really skews numbers
I am just using the movies above solely for midnight comparisons. the box office will react similarly to some of these films (and others) starting today.
I'd think if Zootopia comes in well below $500k, that isn't a great sign for breakout (but then look at Lego). if it comes in above $700k then I think it's well on it's way. just my opinion. hope it helps a bit.