I used the latest version of
Ari Marmell's Spell Sorter spreadsheet to check the spell counts for the various classes' spell lists against the cards and the counts advertised on the decks' tuckbox back covers.
The Paladin deck should have 45 spells according to the PHB's Paladin spell list:
the tuckbox's back cover says the deck has 44 cards, and mine does indeed have 44. The card that's missing is for the 5th-level spell
destructive wave (PHB p. 231), which is erroneously called
destructive smite in the Paladin spell list (PHB p. 209).
The Ranger deck should have 46 spells according to the PHB's Ranger spell list; mine has 46 cards, matching the count on
the tuckbox's back cover, and doesn't seem to be missing anything.
The Arcane deck should have 231 cards according to the PHB's Sorceror, Warlock, and Wizard spell lists: those lists actually include 232 spells, but the designers have confirmed on Twitter that
trap the soul should have been removed from the lists (as it's not described in the PHB). My Arcane deck lists a count of 230 cards on
the tuckbox's back cover, and I count 230 cards. So it looks as though
mislead is the only arcane spell that's missing.
(Note for anyone who wants to check my work: the Arcane deck doesn't include cards for spells granted by Warlock patron special abilities, like
command or
dissonant whispers: it only includes spells which appear on the Sorceror, Warlock, and Wizard spell lists. On Ari's spreadsheet, filtering for blank values in the "Sub-Class" column excludes these special-ability spells.)
