Puzzle

 ACROSS

  1 Pollution-regulating org.

  4 Really good time

  9 Often-animated pic

 12 Z's point value in Scrabble

 13 Diameter halves

 14 Historical periods

 16 *"It was a minor slipup!" (see letters 1-7)

 19 "Glad to hear that"

 20 Advanced animation FX

 21 Makeup-removing swab

 23 Shoe store section

 24 Groups of three

 27 Any nonzero number divided by itself

 28 *Gathering for Eagles (4-10)

 31 Drive-up ___

 32 Words beforehanging up

 33 Bryant of "SNL"

 34 16th president's nickname

 35 UFO crew

 36 School zone sign

 38 Atlantic crosser of 1492

 41 Tiger Woods' grp.

 44 *Body system with bones and tendons (5-11)

 47 NFL official

 48 Plant manager's field?

 49 Fool

 50 ___ von Bismarck

 52 Low-visibility condition

 53 PlayStation maker

 54 Dressing room switches, and a hint to the starred answers' indicated letters

 59 Hip-swaying dance

 60 Making tons of noise

 61 Consume

 62 Dreidel, for one

 63 Singer Lauper

 64 Free of humidity

DOWN

  1 "And so forth" letters

  2 French automaker

  3 Opposite word

  4 Raised

  5 "Leaving ___ Vegas"

  6 Commotion

  7 Metropolis-managing video game

  8 Reason for extra innings

  9 Hairstylist's aid

 10 Kuwait's northern neighbor

 11 Fun piece of trivia

 15 Thin

 17 Growth on a damp rock

 18 Fries or slaw

 22 Coat rack projection

 23 CEO's degree, often

 24 Cigarette puff

 25 Massage

 26 Washington airport

 29 Stringy Halloween decoration

 30 "___ the season ..."

 34 Internet gateway since the '90s

 35 One-of-a-kind gift site

 36 Rough drawing

 37 Omitted

 38 D.C. area river

 39 Mental pictures

 40 Convent resident

 41 Took a nosedive

 42 Time off before college, say

 43 "___ you sure?"

 44 "No seats left" initials

 45 Common meat substitute

 46 Japanese noodle

 51 Capital west of Stockholm

 53 Loose Indian garment

 55 "What's on ___?" (bar query)

 56 Swindle

 57 Consumed

 58 Messy space

Solution