Alas, Poor Villain: Loyax, Villamax and Kegler, definitely. Treacheron too, to a lesser extent.
Ass Pull: Nearly all the Rangers' weapons and gear are given little to no explanations as to how they got them, though most of them have at least some explanation. The Quasar Launchers take the cake, however; they simply appear out of nowhere with no background story provided (the Rangers casually summon them, as if they have done this before, even though this is the first time they appear). But, keep in mind, production was quite a mess to say the least...
The script for the episode specified that they were to get them by holding up their Quasar Sabers and Transdaggers together and then see what happened. Clearly, they didn't film that.
The Lights of Orion are also quite an offender when it comes to this trope. In episode 6 we learn that Furio has suddenly switched his attention from trying to get the Quasar Sabers to trying to get the Lights of Orion, which are apparently on Terra Venture somehow. All we ever learn about them in the episodes that follow is that 3000 years ago Magna Defender released them (on Mirinoi, evidently, since he was trapped in the chasm immediately afterwards). How they ever got on Terra Venture or how Furio found out they were there remains unknown.
Complete Monster: Deviot, in a show full of villains with standards, had none. He was a manipulative, treacherous Starscream who would cheerfully throwaway his men's lives, thought brainwashing was a useful tool, and had no loyalty to anyone. When Scorpius wouldn't allow him to enter the cocoon, Deviot arranged for his death. When Trakeena, and not he, inherited control of the army, he sends two of his men to kill her; when she survives the assassination attempt, he kills the assassins to cover his tracks. He later brainwashed Loyax into fighting the Rangers, leading to his death as well. Deviot ambushes Trakeena, forces her into the cocoon, and fuses with her. The absorption of his evil soul drives Trakeena completely over the edge, leading her to murder her mentor, Villamax, use her men as suicide bombers, and try to regain her human form by stealing the Life Energy of others. Totally untrustworthy, and out only for himself, Deviot proved that on his own, or influencing Trakeena, he could do more damage than any other villain in Lost Galaxy. He was without a doubt the Darkonda of Lost Galaxy in every possible way.
Draco in Leather Pants: Deviot gets this treatment from the fans at times. He gets extra bonus points because Amy Miller, Trakeena's actress, has gone on to say that Deviot was her favorite monster in Power Rangers, despite the fact that he did nothing but try to undermine and backstab her character the whole time.
Ensemble Darkhorse: The first Magna Defender for being the first truly morally gray "hero" in the franchise's run.
Kendrix is among one of the most loved Pink Rangers due to her Heroic Sacrifice.
Evil is Sexy: Trakeena. Leo and Damon even admit while being tied together they think she's attractive.
Even if you take the real world out of the equation, there's still Lord Zedd sarcastically asking Finster once if the monster he had this time could blow itself up. Funny jab at the Once an Episode conventions of the show the first time you watch it. Not so funny if you go back to said episode after watching the finale of Lost Galaxy.
Also, in regards to the above scene with Trakeena and the wrench? The guy is Damon, whose actor later married Trakeena's actress.
In Power Rangers in Space, Karone, when she was still Astronema, kidnapped Ashely and impersonates her to destroy the Space Rangers from within. After that plan fails, she scornful exclaims, "I wouldn't want to be a Power Ranger anyway!"
Gets an equally hilarious Call-Back in Super Megaforce: "I love being a Power Ranger."
Like You Would Really Do It: Yes, this is the first -and thus far only season- to show us the onscreen death of a Power Ranger. Yes, it was a factor of Real Life Writes the Plot, but after 6 previous seasons where Rangers would survive every attack thrown at them, even when they were unmorphed, it came completely out of left field.
Moral Event Horizon: Trakeena crossed it when she attempted to attack Terra Venture with Stingwinger suicide bombers. And she targeted the escape pods, too. (Villamax, a Noble Demon even more so than Diabolico, and who trained her, tried to stop her because his Morality Pet child friend was on one. She killed him, with him refusing to resist out of loyalty.) Do note that this is after the merging with Deviot, so it's either Trakeena crossing it herself, or Deviot was crossing it for subconsciously pushing Trakeena to do that.
On his own, Deviot crosses it for lying to Scorpius that the Rangers kidnapped Trakeena, leading to his death so that he could enter the cocoon and take control of his army. Eseentially, he used Scorpius' only redeeming quality, his love for his daughter, to kill him.
Narm: Mike's death in the first episode is a very well done, emotional scene...until Damon starts shouting his name, looking just as distraught as the others, despite having no idea who Mike is.
Nightmare Fuel: The reveal of Trakeena's evolved form. Helped by the tense music, eerie lighting and occasional momentary appearances it has in the buildup and the fact that Leo is both unmorphed and alone when she finds him. The fact that the suit, an original costume made for Lost Galaxy, is genuinely unnerving to look at helps.
Replacement Scrappy: Averted. Though already well-liked by fans, Karone becoming Kendrix's replacement as the Pink Galaxy Ranger was well-received.
Slow-Paced Beginning: Like most Ranger series, early filler episodes may put off new viewers, but, when the Magna Defender shows up, the show gets really good, and, moreover, for the most part, it stays good.
Special Effect Failure: The magic spell used to turn Mirinoi's inhabitants to stone is an obvious Photoshop filter.
The rest of the CGI doesn't fare much better either. Most glaringly with the digital version of the Terra Venture looking low-rez and untextured (compared to its model counterpart, which for the most part, looks well done for a low-budget series). Some of the terrible CG and effects work, like those regarding the Zords, can be attributed to the original source material, however.
Additionally, the box that originally contained the Lights of Orion is a modern lockbox. Even more baffling is that it's initially located in a more ancient-looking treasure chest.
The compositing can look quite terrible at points. This is most visible during "An Evil Game" when Leo manages to escape from Trakeena, where the insertion of the various elements look extra blurry and hard to make out.
They Wasted a Perfectly Good Plot: The Terra Venture should have gotten accidentally sent to the Lost Galaxy much earlier, and the rest of the series would involve them finding a way out. Which might have been the original intention (see Troubled Production in Trivia).
Vindicated by History: Inverted. It used to be known as one of the best Power Rangers seasons at the time when it first aired but fans becoming more aware of it's flaws and having morepopularseasonssince leaves Lost Galaxy in a strange middle ground, considered better than average but not well liked enough to be a fan favorite.
That said, it does still have many fans who consider it to be one of the best seasons of the show, likely due to it having a slightly darker tone than most of the subsequent iterations.
What An Idiot: Yes, Trakeena framed Treacheron, but does he seriously think that killing the boss's daughter is a good idea? Not that it matters as he dies before Scorpius ever found out he attempted it.
WTH, Costuming Department?: The Lost Galaxy Rangers are often referred to by fans as 'the Charlie Brown Rangers', due to the odd choice of coloring that makes them look like they're wearing stripey jumpers. (Again, you can blame the Sentai for this.)