Synonyms for At first glance:

• adj.

  •extemporaneous/extemporary (adjective)
  • free,
  • casual,
  • automatic,
  • makeshift,
  • offhand,
  • snap,
  • immediate,
  • off the cuff,
  • unpremeditated,
  • made-up,
  • spontaneous,
  • informal,
  • winging it,
  • unstudied,
  • unprepared,
  • impromptu,
  • expedient,
  • unplanned,
  • ad hoc,
  • extempore.

• adv.

  •all (adverb)
  • at first glance,
  • at first sight.
  •superficially (adverb)
  • carelessly,
  • partially,
  • casually,
  • externally,
  • skim,
  • apparently,
  • hastily.

• Other synonyms:

  •Other relevant words:
  • outwardly,
  • surface,
  • extrinsically,
  • to all appearances,
  • ostensibly.

Antonyms for At first glance:

• adj.

  • extemporaneous/extemporary
    prepared, read, written, Rehearsed, planned.

• adv.

  • superficially
    carefully, thoroughly, deeply.