I didn't realize at the time who Leonard Nimoy was, so his playing the voice of Galvatron was a bit of a surprise much later.
Jazz (a Porsche) and Cliffjumper (a red Volkswagen), on one of Cybertron's moons. This whole bit is a sort of introduce-the-characters bit. Most of the characters to this point (excluding the scene with Unicron before the credits) appeared in the TV series and had more or less been part of the original (comparatively cohesive) overall plot. Most of the original characters die during the movie -- that was difficult to accept at the time, and it's really annoying now -- the tendrils of the toy companies trying to sell new and more cheaply produced toys.
These toys were hard to make. They involved a lot of moving parts, metal pins, hinges and detail work. That sort of thing does not a nice tidy cut-rate profit-driven market effort make. Most of the toys made after characters in the movie, and afterward, were substantially simpler, cheaper toys of poor quality, where both robot and vehicle shape were dictated by convenience of manufacture, rather than by an overall design or aesthetic.
Here's Megatron, the Diabolical Leader of the antagonists. Megatron the toy transformed into a handgun (it helped the violence aspect that all the good robots transformed into peaceful things, most of the evil robots into warlike objects -- this all changed after the movie). The toy's robot shape was sufficiently muddled that the animated character just made up something that had a few of the general characteristics (e.g. the gun barrel on his shoulder) to get the gist across. The glowing effect at the left was a monitor screen; one of several instances of this effect that cost more money to make than was expended on the TV series. On Megatron's forearm is Laserbeak, a raptor-ish robot that flew around and spied on things to provide plot. Laserbeak the toy was one of a few that turned into microcasettes, which could fit inside Soundwave, a Decepticon toy who transformed into, well, a tape recorder.
Starscream, the demi-villan. Starscream's role was mostly to be a wannabe traitor. He transformed into an F-15 fighter jet. The toy involved an unusual amount of metal and quite a few different materials to make, and was discontinued after he (and all the other characters whose toys were made that way) died during the movie.
The Decepticons attacked an Autobot shuttle headed for Earth, with the idea of sneaking past the Autobot City defenses with it. Here they kill off Prowl (a policecar), Ironhide (a van), Brawn (a jeep) and Ratchet (an ambulance), all from the early series (Ratchet had a fairly significant role in the comic series.) While this scene was done up to be a bit dramatic, the flame thing coming out of Prowl's mouth was a fairly dramatic/scary touch for children our age -- looking back on it, I suspect again it was done to erase him from our minds in a brief flash of aversive horror preceeding exciting fireworks.
A recurring theme in both series and movie were these curious tactical heads-up-displays, generally indicating the targeting of laser guns. Here, Hot Rod (a sportscar who becomes the leader of the Autobots at the end of the movie) is being aimed at by a Decepticon tank. I have since then often wished for a heads-up display myself. For some reason, the digits in the lower left cycled through a short sequence, which in most of its elements consisted of anagrams of the first five digits of pi and e.
The past, the immediate future, prehistory